You misinterpreted the entire meaning if you think this. The "poor" sub-basement family of conmen were fascist class traitors who betrayed the actually poor basement dwellers who worked hard and were in debt, and they got their comeuppance and a mutual destruction of the rich and poor classes instead of a successful revolution. It's a story of class betrayal, the dangers of lacking solidarity and the futility of selfish behavior to climb the ladder. A warning and fable based in Marxist framing. The central magical macguffin, the rock, symbolized class mobility as it was given by an upper class friend to the main character at the same time he gave him a job offer and foot in the door for upward movement. That rock then was his own downfall as he tried to use it to murder a fellow proletariat to secure his position as a lackey of the rich, fumbled it, then was violently smashed by it used against him. Then he had permanent brain damage freezing him in a deluded mindset of upward mobility.

It should also be considered in it's uniquely South Korean context, the director was not that subtle about the basement family being DPRK. There was a whole scene about it. This entire movie is a reflection on the South Korean left's failure to fulfill reunification, and predicting an upcoming mutual destruction. The housekeeper even begs the mother as a sister, as a fellow worker, to not report her and her husband for hiding in the basement. In response, the mother turns to call the police and turn them in. This is the main moment of failure, the betrayal. The other was getting her and the driver fired and using allergens on her and gaslighting the housekeeper of course, that's the Korean War (biological weapons and class/national treason from the South Koreans, the main characters of the film and the intended audience). This is the turning point of everything, and it also represents the missed opportunity to reunify and go socialist afterwards by uniting against the rich family to usurp them together.

If you don't believe all this is intended, Bong Joon Ho's other films are allegories of revolution where the back of the train kills there way to the front of the train - and The Host, a horror movie where the repugnant monster represents American occupation. Neither are nearly as subtle as Parasite, they're much more on the nose. In South Korea it's illegal to express any positive opinion on DPRK directly, so this sort of allegorical indirect message is the farthest one can go.

Wait you're not joking?