If you measure everything in terms of dollars, you're missing the point to life!
Everybody has a different perspective on boat ownership. For me, it's alot cheaper than my ham
radio hobby where I can easily spend $12,000 on one
radio which hardly ever gets used. So what? I like it!
For many, a big part of boat ownership is the analog to a second home on the ocean. A boat is usually much cheaper. Additionally, a boat doesn't always have to be at sea to be enjoyed - we have spend many enjoyable weekends at the marina without ever doing out.
If I were to calculate how much it costs me to play golf the few times a year I do, I'd shoot myself for stupidity - that's not the point.