There are 5x more households with trucks than households with boats, so this hardly explains it.

There are a lot more uses of a truck than towing a boat.

Usually the imagined uses are very aspirational at best. The imagination doesn't fit reality. I've seen it firsthand, many years ago my dad got the fancy pickup because he "needs the utility." Whenever an opportunity presented itself for him to use his truck as a truck though, he'd pay the extra fee for delivery because he didn't wanna bother.

It did make his reckless driving more dangerous for the innocents, though.

I'll go further, Most Americans who buy stuff like boats don't use them anywhere near enough to justify the purchase. I'm pretty sure well less than 30% of boats are being used at least once a year.

America is so full of hoarding and objects that go years without anyone touching them. It's profoundly sad.