Karl's description is pretty funny, but our situation in the northeast is a mix of ages and stories.

Our fleets teams range from 25-30 and 45-60. They include generally well-to-do to the nearly broke. My take:

1) Teenagers: No mean$ for a competitve cat, and daddy is generally too fat and out of shape to consider a cat as a ride or family expense. Unless Wifey is hard-core sailor, she wants a family cruiser or other 4ksb for the family. (Those 4ksb's are non-threatening, and don't mess up your hair/make up.
2) 20-25: underrepresented generally because of college costs. We have a few, but even a $40 entry fee and gas costs can be a barrier for college kids and parents. If they cannot find cheap lodging at the regatta (unless affiliated with yacht clubs), forget about it. Add to that the high cost of a good boat, and well, a season of competitive sailing represents a big cost against school. These guys are found on lasers or Corinthian boats they can bum from a variety of sources, ore can buy pretty cheap.
3) 25-30. Many guys get married. Unless shis wife/GF is a hardcore sailor, (and there are a few in our fleet), he's going to be spending time either with her or his new family. Babies are a big deterrent to sailing.
4)35-40. Toddlers are a bigger deterrent to sailing. So are extraneous expenses such as sailing when weighed against baby clothes/diapers/family vacations at Disney. (hmm, sailing, $daycare, sailing or $daycare, what to do?) The lean years for any sailor...
5) 40-45. Dad, if he has money, might buy a boat and attempt to get his wife or kids or both on the boat. Neither are ready to race, but they day-sail.
5a) Divorced. Gets a boat, out having fun again.
6) 40-45-50+ If he's lucky, wife or kids like racing/ and the culture of beach cats, and they show up at the regattas.