But if you're a competent politician you recognize that you have biases and attempt to see situations objectively despite your bubble.
You might not get the correct picture, but you'll get far closer than the politician who doesn't even realize he's in a bubble.
Then there are politicians who have no motivation to see things clearly, they just want to look out for special interests.
Yes, I imagine that pretty much all of them want to see things objectively despite their bubble, just like pretty much everyone on this site
wants to see things objectively, despite their bubble. Sometimes they fail spectacularly at that, though, and sometimes they only fail a little bit, which still gives them a skewed view of things.
We all think that our positions are the sensible and mainstream ones and we're all subject to a confirmation bias where we, even unconsciously, pay more attention to those things which reinforce our beliefs. When there is so much diversity of thought and opinion out there and it's very hard, if not impossible, to truly nail down what an actual mainstream opinion on a topic might be and strong arguments could be made that any one of several conflicting ones are that, there's no real reason to assume that one of the non-sensible choices is the mainstream one as opposed to it being the sensible one that you already have because you're just so darned smart and level-headed.