I would assume because moving yachts requires a lot of planning, so he'd likely have one in each location he wants to stay.
Not excusing this behaviour, but there is a reason for it.
My guess is he's treating them as collectibles. If he can afford another, different yacht from the ones he already owns, he buys it. It's a passion.
One needs more than one yacht. Once you've hosted a massive orgy, you need a clean and sanitary retreat to escape to while the first one is worked on by your cleanup crew.