Not intending to present this in any confrontational manner, I think it would be a mistake to read the film as presenting only a loathsome underclass revealed under a surface of pristine opulence. The idea that the poor Kim family is the "parasite" of the title, leeching off the blind ignorance of the wealthy Park family, is only one read of that parasitic situation the movie presents; and I think it's only meant to be a first read, ultimately surrendering the stage to a more complicated presentation of class roles across recent South Korean history.
The scenario of the film seems immediately more complicated than that in the film's first scene, where we see the Kims living in uncomfortable, squalid conditions––but not conditions of absolute suffering. The Kims' problem, which will propel them into their complex larceny scheme, isn't that they're starving; they aren't desperate at all, but they are hunting for something. In this first scene it's an internet connection they can steal. Key to the positioning of the Kim family is that they are all failures. Each of them has failed at some major goal, from the parents' bakery to the son and daughter's failed attempts at education and degrees. These are pretty simple goals for the characters––in fact, they're absolutely cliched dreams, and one of the most poignant aspects of the film to me is how even as these characters dreams grow, they never become very individualized, with each new dream being something someone else provides for them. Ki–woo's dream, for instance, of marrying into the Park family, is stolen outright from his friend (Min?), who introduces this goal as his own before Ki-woo has even hatched his plan. But the recurrent theme of failure in the Kims' lives is reflected in their search for leeched internet, and framed in the context of where they live––nearly buried underground, and so unnoticed that people are constantly urinating on their apartment. These characters aren't implementing this plan they hatch in order to survive; it's because as they are, they are nearly invisible within their environment. This theme of burial will gain some resonance later in the film, when the Kims discover the former housekeeper's husband buried in the fallout shelter, but I think Bong is able to add an extra valence to this theme when he reintroduces it, because the former housekeeper and her husband are clearly coded to be from an earlier era, a generation older than Kim Ki–Taek and his wife. The housekeeper and her husband sing old fighting anthems from the Korean war, which they sing by heart together, symbolizing this generational remove further. They come from an era of war and scarcity, and they have a harder edge to them than the Kims (not coincidentally, when they gain the upper hand over the Kims they act like the unabashed dictators they knew from their youth––something which the Kims, growing up in an era of economic development and further democratization would never even think to do), and a kind of craziness that I think it's implied is a result of percolating in this basement, this hidden form of living, for so long. The time in solitary (the wife experiences this in a way, as well) means they are warped––locked in a childhood world where threats exist on all sides, and behavior is extraordinarily codified. Just as the Kims would never think to use leverage in the petty, dictatorial ways the housekeeper and her husband do, the housekeeper and her husband would never think to create the complicated scheme the Kims develop, all to be able to participate in the world around them––in fact, the housekeeper and her husband view the Kims as morally in the wrong, even though they are themselves perpetrating a similarly deceptive, though altogether less ambitious scheme.
But I think there's some poignancy to the Kims' big dreams, even if they are leeched from the environment they have so fragile a purpose within. So much time in the early portion of the film deals in sidelong ways with how the Kims each seem to "come alive" adopting their ersatz personas in their scheme. Ki–Taek's joy is especially evident when he's in the car dealership, and afterwards during his test drive. And each of the Kims seem to bask in the feeling of being valuable to the Park family. This gratifies them so immensely, because in fact they want to be seen. They want to take part––this is what's been denied them by their failures, and by they're being poor. But their joy has a bitter aftertaste they don't notice at first. I think if you were to divide the film into two halves, as cpetrizzi is suggesting, you could divide it into a Part I, in which the Kim family gets their mojo back, and swells with pride at their ability to be a recognized, valuable part of their environment once again, and a Part II, in which the Kims come to realize that their newly reclaimed visibility comes at a more serious price than they realized; they are only visible so long as they are in these borrowed identities. As themselves, as a family, they are still invisible; this complication is first introduced when the Kims discover the former housekeeper's husband, and come face-to-face with their own doppelgangers. At first the husband seems to reflect back upon them the invisible identity they all bore before. He is the ultimate in invisible––someone so hidden away that all of society believes him to be dead. He is, moreso than the Kims, a truly pathetic failure, unaware of how miserable he has become. He even had a bakery of his own that folded, and Ki-Taek especially identifies with this demented figure, staring at him aghast and fascinated (and he'll ultimately take the man's place, enshrouding himself in this ultimate invisibility at the climax of the film). That the two of them both know morse code links them together a little closer, and it's Ki–Taek who is the first of the Kims to begin to crack, the first of them to be unable to continue his facade after coming face to face with someone so much like himself, and so scary to him at the same time. In the scene following this the Kims hide under the living room coffee table, becoming even more uncannily invisible to the wealthy and successful Park parents, who spend the night right above them without ever seeing them. There is a way in which, once the Kims integrate into the Park's household, they become invisible for a second time, and they each have to deal with what this means. Ki-Taek becomes increasingly distressed, which is expressed in the way he lingers over the Park family, trying to figure out the emotional motivations they have behind the demands they make of him ("I guess you're doing this because you love your wife..." he babbles to Mr. Park; "you must really love him" he says to the wife, talking about the husband––both of the Parks misinterpret Ki–Taek's utterly benign intentions at these moments––the wife is creeped out by the intimacy of it, and the husband lets Ki–Taek know he's being paid extra at this moment, so he should buckle down to work with a smile on his face [the work at this point is for Ki–Taek to dress like a Indian and raid the Park son's teepee––it's interesting how the work the Kims have to do for the Parks gets progressively more unreasonable, involved and demeaning]). The son, Ki–woo, reacts to the encroaching invisibility of a life of servitude by doubling down on his plan. Instead of aiming to be a gracious servant, now he means to intrude into the Park household by means unable to be ignored; he means to marry the Park's daughter. When Ki–woo announces this desire it seems like a trespass, an overreach that deserves some rebuke; it is at about this point in the film that thunder rumbles and it start to rain, and the mounting deluge, combined with the increasing plot complications of the former housekeeper and her husband––and ultimately the flood that evicts the Kim family and leads to the revealing of who they really are in front of the Parks––all seem like payment for Ki-woo's grand ambition (and in fact, the loss of his sister seems to be a direct, almost Freudian form of karmic payment for his desire for the Parks' daughter). Ki-woo imagines his success will lead to a greater achievement yet––he doesn't perceive that the divide between him and the Parks is essentially an unbreachable gap. He believes his success in becoming their servant will necessarily lead to success in stealing what he imagines to be a greater role. The Parks' daughter sees him as a paramour. Now he needs the entire family to see him as one of them. Yet the events of the second half of the film unseat his confidence in his plan. He worries as he looks out at the Parks' impromptu gathering that he doesn't belong amongst these people. He can't imagine a further downfall waiting in the wings.
If the limits of visibility provides the key dramatic hinge to the Kims' story, the Parks are also revealed by the limits of their own vision. Their neighborhood is situated on a geographical rise (so that their runoff runs down the poor neighborhood, as we see during the rain scene), but their own house is on a man-made butte above the rest of the neighborhood. They are gated–in, and surrounded by thick hedges, and while that means that no one can spy upon their lives (unless they were, for instance, a servant in the household, or a ghost living in the secret bomb shelter under the house), it also means they can't see out, either. When the Parks decide to sleep in the living room, keeping an eye on their son in his teepee, their view of the outdoors consists of the teepee, the lawn, and the hedge––nothing else gets in. If they are more precious and mannered than the Kims, more trusting and more gullible, it is clearly because they lead more myopic lives, in which they interact only with the members of their own class. Younger than the Kim parents, the Parks don't seem nouveau-riche––they seem like people who have grown up succeeding, doing better and better. They are so far removed from the era of the Korean war, for instance, that remnants of that era––the former housekeeper's husband, for instance––are like fairy tales to them––ghosts to scare their children. The Parks seem stupid, even in the context of this movie, because they can't see the things even right before their eyes. They don't notice the former housekeeper's husband coming up the stairs and stealing food from them at night; they don't see that their new house staff are all members of the same family, that none of them have the qualifications they claim to have, or that as they make love on their couch, this invisible family is right below them, and, buried a couple of stories below are the remnants of a past they have no experience with and no access to (in fact, they don't even know the bomb shelter is there under their feet. But I think the film makes it clear that the Parks' seeming stupidity is really a profound limiting of vision––it's not that they couldn't see all these forces moving around them, but rather that they couldn't even imagine them doing so in the first place. But even though their privileged social strata keeps them even from the need to see the forest from the trees, they do have what the Kims want; they are always visible. Successful people are valuable people, and so the Parks needs are always met; they can always participate, always integrate themselves into what's happening around them if they so choose. The Kims, in their poverty, are completely isolated––even from other poor people. They have no neighbors who would show up for an impromptu birthday party, for instance; and what community they have is obliterated by the end of the film, when the whole neighborhood gets flooded, turning them into refugees of disaster––yet a greater helping of invisibility. But the Parks' success is based on the literal bedrock of a bomb shelter, where members of the war generation remain huddled in hiding (and the architect who built the house is also identified with the housekeeper and her husband in that hardscrabble generation––he isn't equated at all with Mr. Park, even though both are successful architects––that original occupant of the house built the shelter to hide from bombs falling, or from debt collectors, and we sense that Mr. Park has never worried about either of these things). In a sense, the wealthy Parks are as much the parasite of the title as the Kims might be. No matter how close a physical proximity the various characters get to one another in the film, they are always held apart not only by class, but by experience, and the different generations in the film are only ever given to only see the world from one vantage point. It is the Park's blithe ignorance and life-long comfort that allows them to ignore the plotting and scheming of those less fortunate surrounding them. But the two poor families of servants, rather than being united by their suffering, are natural enemies, because their outlook on the world around them is palpably different. In the differences on display you can see a whole recent history of South Korea, a transition from an oppressed peasantry to an industrial society, from an industrial society to a 21st–century mega-economy; and in it, each generation remains stuck where they are, unable to cross barriers of class and become visible to one another, because their different outlooks mean that they refuse to admit the real existence of one another.
What does the violence at the end of the film mean in terms of this angle of approach? It seems to me to be karmic payback for the Kim family beginning to overstep their roles. Ki-woo is too ambitious, planning to marry into the Park family. Ki–Taek is increasingly empathetic with the Park parents, wanting to deal with them in the kind of emotional exchange only available to economic and social peers in a stratified, industrial society. Ki–Taek's wife is perhaps a little too facile as the housekeeper––she is the one who most effectively hamstrings the former housekeeper and her husband, and she can be seen to be paying for that as the vengeful husband of the former housekeeper murders her daughter. The Kims' daughter pays with her life; her facility makes so much of the Kims' plan possible, and it's ultimately useless to her against this aggrieved maniac, a relic from an era before she was born. That the Kims don't see this reckoning coming is also due to the limits of their own vision; they don't perceive the chain of damage they're perpetrating by being imposters. Even as they begin to recognize that servitude is just another form of invisibility, they still can't see their plan unravelling in spite of their own cunning. In the end, as Ki-Taek looks and Mr. Park, he realizes that Park suddenly sees who he actually is. His distress at his dying daughter reveals him. The reaction Ki–Taek has is a mix of panic and his frustration at being unable to save his daughter––the murder he commits drives him underground, to take the place of the former housekeeper's husband in the ultimate form of invisibility. In the end of the film Ki–Taek is figuratively "buried alive." It is not accidental then that his son Ki-woo's final plan is for his father to emerge again into the light; to finally become visible, in visibility to become respectable, noticeable, present. I thought that was rather moving. As for the portrayal of the poor characters as conniving, I didn't find it aberrant. I admired their cunning, their wits, their good humor. I wanted them to succeed with their scheme. I felt for their plight at the end. They are living dead at the end of this movie; useless, with no impact within their own society. The Parks need never know exactly what happened to them. They can continue their lives elsewhere, a little sadder but probably no wiser. But Ki–woo is back at the end of the film to where he began the picture, scheming for a way to bring his family out into the light. To me the film is not just a contrast of rich versus poor, but rather and exploration of how those conditions alter and affect what you see in terms of where you are, where you've been, and where you're going.
