In both of my examples, I can think of instances where a person is or is likely left leaning. Granted those small populations, but they're more sizable than you'd think. Some of us found people willing to write a $10,000 check on a whim (I was not that lucky). These people were very much not Republicans. Saying something is due to "human nature" means pretty everybody does it. If anything, of the groups I'm talking about, I'd say far more are quiet than loud. They vote and donate Democrat but don't necessarily make it their entire personality.

I don't know about nationalism being boosted by being rich. If anything, these people have more interest in global investments and wider view of the world than people without a direct reason to be so. I think that might make some of them more realistic about nationalism. I also see plenty of it among those much less fortunate - it's emotional thing heavily inculcated by wider society. Questioning is still largely socially unacceptable.