The more they get paid, the easier they are to bribe. Money becomes less of a thought, they don't see the problem with getting a trivial sum from someone, it isn't helping them much.
Mate, read the logic in what you wrote - how the hell do you bribe someone with something you say they don't want? Having said that I actually agree that most politicians don't care about money, they care about power. Money is a powerful tool but political power trumps it.