Billionaires aren’t necessarily bad people, and most of them probably aren’t. However, some are, and my unscientific sense is that billionaires are more likely than the rest of us to exhibit bad judgment warped by runaway egos, especially in the political sphere.
It’s not hard to see why: Great wealth attracts people eager to tell an extremely rich man (or woman, but political egotism is mainly a male thing) what he wants to hear. In the political arena this means telling billionaires both that their lavish financial rewards are a mere fraction of the vast contribution they have made to society, and that the public is clamoring for them to take their rightful role as leaders.