Is this even a question? 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.
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.