The Robber Barons also contributed immensely to society. Their money helped create arts endowments, public libraries, conservation lands, colleges and universities, etc.
Some did yes. Others contributed to local infrastructure for personal reasons.
But much like Bill Gates and his generosity, it's an exception and not the norm.
Plus Rockefeller (the first to come to my mind) is a poor example due to being basically the richest man in all of history.
I was actually thinking more about Andrew Carnegie, J. P. Morgan, and Cornelius Vanderbilt than Rockefeller when I commented. But all four were fairly philanthropic once they made their fortunes. I think their philanthropy set the standard for the weathiest people to follow. It's also expected in capitalism that the wealthy voluntarily contribute by giving to various charities that help the lowest classes. That said, pure capitalism, much like pure communism, fails to acknowledge the power of greed. So yes there are wealthy people who are more consumed by greed and hubris but there are also many wealthy people who discreetly donate a decent portion of their wealth to various charities.
This enabled the Robber Barons of the 19th century and lead to the current anti trust laws.