What was the difference between the rich and the poor family? Who is the parasite? What is it exactly that the rich family does better or gives to this world that they deserve the exceptionally better lifestyle?
Are they more intelligent? Surely not, since they were duped by the other family. Do they really care about other people and what's going on in their surroundings? Not really, they never bothered to figure out any of it, they are blissfully unaware of the of the less fortunate, untouched by the reality around them until it affects them directly. They don't care who serves them. Are they more virtuous? Not exactly, look at how they behave on the party when the girl gets stabbed. The dad takes his boy who fainted and tries to pick up the car keys, all the while pinching his nose in disgust of the 'poor people smell'. Does he help any of the wounded people? What are their actions?
> The rich people were never mean or overbearing to less well off people and treated their workers well.
How about the part when they act like they own them? One example is dad having to wear a costume for the boy because the boss is paying overtime for his non-working day. The driver dad is not exactly in a position to refuse or he could ruin his position (we saw how easy it is to get replaced), so he has to put up with it, humiliate himself and play the clown. The rich dad doesn't see how this is a problem, money should buy everything after all.
The movie is an allegory and it requires a deeper look and a bit of thinking. Contrast and compare this movie to 'Us', you will find similarities in how it deals with social class.