When he was asked in 2011 if there was anything he would change about what he wrote in his collection of essays, Hackers and Painters from 2004, Paul Graham replied:
[...] there is one thing I'd change. In "Mind the Gap" I implied the reason people were upset by economic inequality was the model of wealth they learned as children. Now I suspect it goes deeper than that: I think humans may have a genetic predisposition to equality.
What made me realize this was going to Africa and seeing lots of animals in the wild. All or nearly all the big mammals lived in groups and cooperated to survive. It was clear that our ancestors would in their day have been one of these groups, also cooperating to survive (as hunter-gatherers still do in a few places), and that their cooperative inclinations were probably genetically preprogrammed.
If so then people's problem with inequality is not a learned behavior. It simply feels wrong to humans.
That doesn't mean they're right. The Monte Carlo fallacy feels right to humans, but it isn't. But it does probably mean that people are happier, all other things being equal, when there is less inequality.
Of course you have to balance this against (a) other, equally deeply held traditions, like not stealing, and (b) the slower technological/economic growth you get when you ban being rich.
This makes a lot of sense to me because after traveling through India, Vietnam, and Nepal in 2010, global inequality just 'felt wrong'. There's no other way to explain the feeling. It just felt wrong.