The observation is certainly correct. Many boats look as if they are never used.
The first reason to come to mind is boat owners getting tired of traversing the same waters. It was to have variety that we purchased (last November) a boat that could easily and quickly both move around the Chesapeake as well as be easily trailered to other waters.
Our previous boat, a trailerable Precision 21 sailboat, met neither of those criteria. For us, getting to the Bay meant a 45 minute trip down the South River. It got old after a while. It also had the potential of being rough (when the tide and wind were in opposite directions).
Hopefully time will show that our decision was such that our boat usage will be much greater than boat owners generally and more like the usage of the c-brats.
It may also relate to peoples expectations... for example, someone who perhaps fishes three or four times a year purchases a boat with plans to fish 6-8 times a month, and then they find they don't really like fishing that much. Or they buy a sailboat and discover the requirement to have adequate wind may not be met that frequently, or the work required to put up/take down the sails starts becoming monotonous and tiresome.
Because boating is not generally a solitary endeavor, using the boat likely means the participation of other family members. This can mean that families with children are going to be minimal boat users even though the children may have been the biggest proponents of boat acquisition. There is so much going on, that there will be tradeoffs between boating and other children's activities (athletics, etc) and I'd guess the more social activities are dominant.
Boating takes time to do well and to enjoy. I have an unproven impression that a fairly large number of the people that boat a lot are retired. Children and jobs both have a high priority and probably result in much less boat use than the purchaser originally anticipated.
Bill.Secure
Edgewater, MD