There are billionaires who buy giant luxury yachts and private islands, but they are not the ones to worry about.
The ones who should be troubling us are the billionaires who care little for luxury, and dream instead of using their billions to control humanity. They are the dangerous ones, with megalomaniac projects, such as the longtermist project of assuring the future of humanity for thousands of years into the future, or Thiel's project to defeat the woke global antichrist. As we saw with Nazism and communism such grandiose projects require sacrifices that are always intended to be made by ordinary people, not the leaders. And, of course, these projects require specially brilliant leaders, or rather leaders who have convinced themselves and others into believing in their brilliance, and for that reason they require the suppression of liberty and democracy, lest ordinary folk block the path laid out by the leader. Having seized immense power the leader, convinced of his own importance, is prone to see his own personal prejudices and resentments as exemplifying issues of world historical significance. So the grand project becomes infected with the leader's personal prejudices.
It is such billionaires who should be allowed nowhere near political power.