Saez and Zucman show that, in America, the wealthiest 160,000 families own as much wealth as the poorest 145 million families, and that wealth is about 10 times as unequal as income.
I have nothing against some people earning and owning more than others; there's good evidence for positive incentive effects, as well as economic dynamism. But that general rule competes with another, which, I'm increasingly convinced is more important to focus on: power corrupts, and the more power one has, the worse it can be abused.