That's one of the things a lot of people like about Trump is the idea that he can't really be bought. He can, but it isn't in the same way as normally wealthy politicians are bought. That's one of the main reasons why the Democrats, the Republicans, and corporations are so terrified of a President Trump. They will have virtually no way to control him. He's grumpy and jerky enough to tell the Democrats to sit down, shut up, and stop whining. He's self-assured and self-financed enough to tell the GOP to sit down, shut up, and stop whining.