You're right. In fact, late 30s and early 40s is generally when people traditionally started companies.

But when I say "start up culture" I basically mean "silicon valley startup culture" and HN is basically that and its fan club. Mostly the latter. It is the difference between being part of "the gig economy" and just a part time/contract worker.

Yeah, there are some older people around here, just like there are at reddit and the like. But just reading and engaging in threads, it is very clear that this also skews pretty young.

And a large part of it is that the people who are in their 30s and beyond tend to either not have time to hang out on a message board and discuss things with kids in college (in my defense, I am between projects and killing time).