They are intriguing questions. We need to separate the descriptive and the prescriptive ones, though. As a matter of fact, Sade and I say, the wealthy and powerful tend to be corrupted by their opportunities to dominate others. Sade justifies that exploitation with cynicism about morality.
There may be ways to stop that corruption, but the systems we've tried have ended up succumbing to what I call the default social order in nature (the dominance hierarchy). Theocracy, socialism, democracy--these systems are like dams to hold off the water, but eventually the dams break and natural instincts take over. The societies become tyrannical or plutocratic, as power is centralized.
Preventing that kind of abuse would require changing our mentality or our nature. That's what Buddhism and the other religions that hold out the possibility of enlightenment try to do, but they seem to throw the baby out with the bathwater. Sure, enlightened individuals are no longer interested in exploiting or dominating people, but that's because they're no longer interested much in anything. They no longer attach themselves emotionally to anything, including themselves.
Their tranquility and contentment are supposed to be better than unenlightened happiness, but the unenlightened masses evidently aren't convinced. They'd rather have the downside of egoism than an arid lack of mental intensity.