I wonder how much of that is because at those wealth levels, you start to feel you don't have much in the way of agency (you're not bargaining for the cost of the superyacht, someone does that for you, etc) - and you want to feel "in the game".

Now if by "owners" you mean the owners of the yacht, then it makes more sense as it's a business and they're controlling costs, especially the ones they see as "variable".