First up, I'd say most of their behaviour can be explained by context more than enduring individual traits.
I call my local legislative assembly (upper house for the State) Senator all the time. It started out that I didn't know, now it's just a joke. He doesn't say anything and responds as if it is appropriate, even though he's technically only "the honourable'' since he's also a Minister. I have no idea whether he thinks I'm a village idiot or having a go at him because he has seen me in contexts that would suggest I'm more politically savvy than I actually am.
I'm pretty sure if I was in his shoes, I might not correct me. Unless I was with rationalists. But then, I'm not in his shoes because the path dependencies of my life haven't taken me there.
It seems that politicians make a lot of decisions that aren't socially optimal because they want money from lobbyists and other campaign contributors. Presumably, the purpose this money serves is to keep them in office by allowing them to advertise a lot the next time they're up for reelection.
So the question then becomes, "why do they want to remain in office?". I could think of two reasons: money and power. From what I know, politicians have a pretty high salary (congressmen make ~$175k), so that's an understandable motivator. But power is the one I don't understand.
Supposedly they want to remain in office so they could use their power to have an influence. I don't know too much about politics, but it seems that politicians spend most of their time catering to lobbyists and voters rather than pushing the things they actually believe in. So much so that they aren't actually exerting that much power. And it seems that most of this catering is to special interests and is socially suboptimal. (I may very well be wrong on these points. I really don't know but it's the impression I get.)
Why are congressmen so motivated to stay in office, make $175k a year, exert a minimal amount of real power, and spend their time catering to lobbyists and making socially suboptimal decisions? I'm sure they could make twice as much in the private sector. I feel like there's something obvious that I'm missing here, but I'm genuinely confused.