I have found that LessWrong has the opposite effect on me. While I think that I am less rational and less intelligent than the average person here (or perhaps the availability-weighted average?), my main cognitive response has been an increase in self-esteem.

Strangely, in college, where there was also an abundance of people smarter than me, I and my response was a general feeling of inferiority.

I would hypothesize (~40% confidence) that the source of this difference is a sense of competing with my college classmates for jobs vs. aspiring to gain the abilities that others here have.