Clearly, you're right. But, you can't blame those guys. Trump doesn't need their money so they have no way of controlling what he might do as President. Even if he were from the other party, they could buy him if he didn't have so much money himself.
They don't want anyone who can't be bought or controlled.
At some point, in the smoky back room.... Trump is going to tell them they either nominate him or they lose.....