More generally, is America for sale?
USG has earnings of some trillions of dollars. At a typical P/E ratio of 20, this means USG is worth some hundreds of trillions of dollars, and America as a whole is worth half a quadrillion.
Does Bezos have a quadrillion dollars?
You probably couldn't buy America directly. Maybe you could trigger a referendum? I dunno. It's hard to see what would stop a quadrillionaire from buying a military coup or suchlike, though. They could fund their own spy agency (staffed with competence) to figure out exactly who would stop them, and then have them Alex Jones'd or Epstein'd. Would it take so long they would have successor problems?
If you have enough money you can even buy a test coup, see what goes wrong, and specifically address the issues for the next coup. Having enough money to buy enough prototypes is merely a matter of accounting and keeping costs down.