The conclusion of industry analysts is while new boaters come and go, the core of long-term sailors is stable. Those of us that become addicted occasionally sell a boat, but then by replacement. That's certainly my story, having owned a beach catamaran, Stiletto 27, PDQ 32, and now a Corsair F-24 Mk II.
Unfortunately, new boat owners come, but mostly go. As a result, boating is in gradual decline. Some point to New Age alternatives--the internet and other sports. Some correctly point out chartering is on the rise--boat ownership and all of the maintenance that goes with it is a good fit with the new generation.
Small boats are still a healthy industry. My daughter, for example, would love a sailing dinghy and I'll bet she'll buy one someday. But you can't see her owning a bigger boat. It wouldn't fit her needs, and the maintenance and fiddling would never hold her attention. I can see that. It feels pretty irrational at times to me.
The result is that we sailors are getting older and older. It doesn't just seem that way, it's true. I'm okay with that. By the time the sail population ages enough that my target market has evaporated, I'll have run out of things to write about.