It is luck in a sense - every way that your opinion differs from someone else, you believe that factors outside of your control (your intelligence, your education, et cetera) have blessed you in such a way that your mind has done better than that poor person's.

It's just that it's not a problem. Lottery winners got richer than everyone else by luck, but that doesn't mean they're deluded in believing that they're rich. But someone who had only weak evidence ze won the lottery should be very skeptical. The real point of this quote is that being much less wrong than average is an improbable state, and you need correspondingly strong evidence to support the possibility. I think many of the people on this site probably do have some of that evidence (things like higher than average IQ scores would be decent signs of higher than normal probability of being right) but it's still something worth worrying about.

Then it would make sense to use some evolutionary thingy instead of Bayesianism as your basic theory of "correct behavior", as Shalizi has half-jokingly suggested.