I guess everyone has a different interpretation of the story, despite some people's claims that the movie was boring. In my opinion, three classes—the rich, the poor, and the poorer—were represented in the narrative. The poorer people I am referring to are, without a doubt, the former housekeeper and her husband. Most people would wonder why the father had to kill Mr. Park, but someone once told me that Mr. Park's subconscious sudden admission that he thought Kelvin's father and the former housekeeper's husband were the same because they both smelled bad was the final straw that caused him (Kelvin's father) to kill Mr. Park.
The film serves as a metaphor for a number of social problems that exist globally, most notably in South Korea. It focuses on classism and how it relates to capitalism, poverty, social strata, and other issues.
Despite the comedic nature of the film's opening, we are thrust into the spotlight when we discover that the entire family are con artists. We are all perplexed as to why the Parks are so clueless, and unaware of what is happening. However, in reality, when you trust someone, you often naively believe everything they say and do.
The movie then attempts to present itself as a thriller, but it falls short in this regard; in my opinion, it actually presents itself as survival horror mixed with comedy horror.