This seems like a difficult case to make. How do you know that none of the many places you're not familiar with aren't smarter on average?

If I wanted to find too-smart, I would go to Less Wrong, (who seem to be smarter than HN on average; that might just be a side effect of the discussion topic) and ask them where they would go to find too-smart. And repeat. I don't think HN is where I'd end up.

http://lesswrong.com/lw/ub/competent_elites/ suggests "hedge fund managers" for step two.