> It also doesn't help, to have rich people, dancing around, showing off their wealth. That tends to breed resentment (see "war").

I agree that this accurately describes observable human behaviour, but not that we should therefore accept that it's morally okay.

In general, if I have a problem that could be solved by you having less of something, that's a me problem, not a you problem. Wealth inequality is such a case. (Anxieties over status are another example.) I want the absolute purchasing power of the poorest people in society to increase over time. If some policy causes that to double, but the APP of the richest people in society to 10x, that's a good policy.