Bribing good people

Most people think they're good people. Michael Moore and Naomi Klein lie and distort routinely, but think this is justified because they're right about the fundamentals ("fake but accurate"). Richard Dawkins also lied, probably for similar reasons.

Hitler probably thought he was a good person. (Or was he a sociopath? Presumably sociopaths don't think they're good in a moral sense because they don't care, though they have pride in their abilities. So Hitler might have thought he was the Neitzschean "great man", for what that's worth.)

One of my favorite posts of Eliezer Yudkowsky's is his reminder that our enemies are not evil mutants:

Realistically, most people don't construct their life stories with themselves as the villains. Everyone is the hero of their own story. The Enemy's story, as seen by the Enemy, is not going to make the Enemy look bad. If you try to construe motivations that would make the Enemy look bad, you'll end up flat wrong about what actually goes on in the Enemy's mind.

I can't reconcile the idea that most people don't think of themselves as evil with my understanding that some kinds of banal evil are so widespread. For example, I think politicians often act according to very self-interested incentives, rather than for the good of their electorates. Alaskan Senator Ted Stevens was recently convicted for accepting bribes. And it's not very surprising. From the population of a few hundred senators and congressmen, politicians are convicted of bribery every year (I think). Presumably they all think they're good people. How does that even work? These guys aren't poorly paid; they can hardly have stood to benefit significantly from increased wealth. Surely the cognitive dissonance from thinking you're good and accepting a bribe would not outweigh the benefit from the money?

I just don't get it. There is something wrong with my understanding of humanity.