I'm not being sarcastic and this is pure speculation.
But for these mega-wealth these are some of the things I suspect:
1. They evacuate in their private plane and:
2. They most likely have their boats insured to the max. Their insurance includes acts of nature. If they leave their boats and things don't work out they total the yacht and make money off the insurance company.
3. Some of these people have a lot of ultra luxury items including more than one yacht. I'm guessing some forget about some of the things they have. They have a managing company rent/lease their boat (or mansions or planes or private islands or whatever) for them and get a percentage of the profits As long as they see money come in they don't care. But when there is a hit on their income they say, "Better looking into that. Oh wow, I have a yacht in Florida I forgot about and it's laying on top of a beach front restaurant now after that storm that I heard about in the news."
I know it sounds stupid but unless we are one of these mega-rich folks we don't know how they think. Anyhow that's pure speculation and maybe I'm way off but the question is a good one and got me to thinking about it.