Even Eliezer Yudkowsky doesn't believe he's the smartest person alive. He's the founder of the site and set its tone early, but that's not the same thing.

Finding people smarter than oneself is essential to making oneself more effective and stretching one's abilities and goals.

For an example I'm closely familiar with: I think one of Jimmy Wales' great personal achievements with Wikipedia, as an impressively smart fellow himself, is that he discovered an extremely efficient mechanism for gathering around him people who made him feel really dumb by comparison. He'd be first to admit that a lot of those he's gathered around him outshine him.

Getting smarter people than yourself to sign up for your goals is, I suspect, one marker of success in selecting a good goal.