A Sharp Line Between Upper and Lower Classes: Zoo Animal

Q: Why does the peasant crave oppression so much?
A: They know they can't survive outside in the wild.

The upper class is defined by becoming stronger and healthier if they get what they want. The lower classes are self-destructive and either kill themselves or deprive their children if they get what they want.

As a result, good advice for the upper classes is diametrically opposed to good advice for the lower classes. 

The upper classes can survive independently, in the wild, outside captivity. The lower classes have more grandchildren if they don't get what they want. They must be raised in captivity or they soon won't be raised at all.

Note that I have no need to define exact percentages. Maybe you want to make a case that the lower classes are no more than 5% of the population. I'm all but certain you'll fail, but this is simply another reason there's no need to oppose the attempt. 

Giving advice suitable to the lower classes to the upper classes reads as an attack. The society betrays their upper classes, which then quite rationally defect on the society as a whole. The peasants certainly aren't going to be able to fight them off, so this is an efficient way of committing society-wide suicide. 

Giving advice suitable to the upper classes to the lower is an attack but doesn't read as one, because they're peasants. They just die. Nobody has tried this seriously enough to remove the lower classes from existence, so I'm not sure how it plays out in the end.