LW is basically a high-IQ club. People with abnormally high IQ get used to being smarter than most around them -- and specifically get used to winning arguments, if not by superior knowledge than by superior logic and rhetoric.

Uhhhh but the whole point of LW is that "argument-winning power" is a very different thing from "entangling-yourself-with-reality power", which is precisely why you can have a very high IQ and still need to learn all kinds of domains, like rationality, or scuba diving, or mathematics.

If you're, say, in the top 1% of the population (by IQ), 99% of the people are not as smart as you. That's enough to make you conceited and contentious :-)

Yes, but that's called being an arrogant asshole, and I personally prefer to do as little of it as possible, especially because I know it's the easiest bad habit for me to fall into and one of the worst for my ability to get along with others, which is very much something I care about.

An Arrogant People's Club is a very bad thing to consider having.