Good question. I haven’t got an answer for that. We could start off by pruning off the top; anyone with a net worth above a billion can’t possibly have earned that kind of money. 900 million is just as unlikely.
A modicum of luck obviously plays a part as well; Facebook for example started off as a fairly innocuous website for ranking the attractiveness of university students; poor in taste and judgement but hardly evil. That’s not exactly where we are today, is it? Have you read about how facebook treats its content moderation team? Ol’ Zucky is responsible for that and so much more.
There’s only so much you can earn through hard work and good luck before you’ll start having to make unethical and evil choices to keep raking in the cash. Rich people don’t need or deserve any empathy, because they won’t have any for you.