That money he gave to politicians is called "protection money." If big businesses do not donate to politicians (of any party), they will destroy the business. It is typical for businesses to give to all top candidates of both parties during an election.
And it is a fact that wheeling and dealing has to happen to get anything done. You are calling it bribery, but it isn't: it is the way things get done, and there seems to be no alternative. Trump knows how to negotiate and he has a solid record of negotiation. Cruz has very little record at all of getting things done, and it seems he supports amnesty, and the ill-named "immigration reform" aka opening the border.
If you don't like the system, supporting the candidate who was cut out of the same cloth as those who created the system is hardly the way to get it dismantled. The only way to do that is to get a smart outsider, who is tough and can stand up to the entrenched powers that be.
the better term for the money to politicians is grease. Grease makes the wheels go round. Trump is a New Yorker where tips are actually grease