You see a lot of smaller boats too, a lot of sailboats too, that are seldom used. Two primary reasons. With some owners, they simply lack the passion for boating they anticipated. With other owners, they simply lack the time and energy. Both spouses work and kids have so many interests. With two weeks vacation per year the norm and three or four less common, when is one going to boat. Then executives who may own the larger boats have even less time, not more. Their vacation plans change at the last minute.
In the US, leisure time is not as readily available as elsewhere in the world and it's not made the same priority. An executive in Europe for a major company will plan next summer I'm going to spend the first two weeks of June cruising with family, leave them and then return to the boat the last two weeks of July. In the US, the similar executive simply can not plan and keep their plans that far in advance.