I started reading OB because I liked Robin Hanson as an economist. I continued reading because I liked Yudkowsky as a writer. I agree I'm still part of an unrepresentative sample (people who are willing to read and consider Yudkowsky's long ramblings), but not everyone found the site because of an interest in rationality per se.

Unfortunately, anyone taking a college course probably would be interested in rationality qua rationality. But the lessons are still valuable for those poor souls who, like I once was, are still religious despite it. The same for those who are religious fence-sitters.

I agree about the unrepresentative sample. It would be interesting to try teaching OB in a small class-sized four-credit college seminar, with a follow-up a year later, to see if the material can be presented so as to have impact on ordinary university students, or on ordinary students at a selective university. Probably worthwhile as an experiment, after we do some more basic research seeing if we can detect this "rationality" thing in a survey or something of the OB readership (so we'd know what to test for).

But even given that OB is starting with all or mostly rationalist wannabes, I'm surprised at the impact its had on my and others' thinking, relative to what happens to rationalist wannabes who don't read OB, or who aren't members of this community.