I don't think that's a useful question, though the answer is generally no. Yachts, or more generally pleasure craft, are a form of entertainment. The owner spends large and ever-growing amounts of money, funding other people's lives, in exchange for some kind of fun for themselves and their immediate circle.

Larry Ellison could certainly make them benefit others by, say, using them to provide housing for the homeless, but that's not a part of the primary equation.

> We should always keep in mind that opportunity cost is a thing, and that investment involves plenty of "spending" and economic activity of its own.)

The economic activity of moving around vast sums of money benefits very few people, and those are generally not the people working multiple jobs just to make ends meet. That's the reason people want a wealth tax: concentrating wealth to such an extent benefits almost nobody.