Having spent my teenage years in what would otherwise be called a ghetto and now living in a wealthier suburb, poor neighborhoods have way more selfish assholes. I'm very glad I got out of there.
I think being an asshole hurts you more than is helps you as you get richer.
Where I came from, the norm was just anger. And the conversation was mostly putting each other down. Or challenging each other. Still trying to overcome that.
At some point in my life, I've been close to both extremes. I've been a poor college student with a family and just barely below the poverty line because of the dependents. I was firmly middle class for my youth and then after starting my business. Selling my business has put me in the upper class section.
There are some broad stereotypes that can be made but the biggest difference I see is in how others respond to you and how the system responds to you.
As a product of private school: my experience is yes and no. There are certainly some behaviors that hurt your success, and there are plenty of extremely successful people who are successful specifically because they are excellent human beings all-around. There are also plenty of people who are financially successful because they are exceptionally selfish and generally horrible to others, but not in overt or combative ways.
So your mileage may vary...
I think rich people treat rich people better and poor and middle classes tend to treat each other like trash but treat rich people like they are gods.
A better comparison is between people in the same social bracket who have relatively more or less money, such as the Monopoly experiment where one player was given an intrinsic advantage.
https://www.ted.com/talks/paul_piff_does_money_make_you_mean