That’s surprisingly hard to do. Even with an exorbitant amount of money. Turns out nation states like to claim large chunks of ocean as theirs. They also get really huffy about “international” waters, that they don’t directly call dibs on.
Functionally, they have a history of sinking in storms. Look up Micronations.
There is arguably a small, virtually inaccessible spot in the middle of Antarctica that may not be covered by treaty. I’m sure Shiden has a base there by now.
Shiden has the money and other resources to start his own island nation and play with with the big boys; it is time to start acting like a non evil version of Dr. Julious No so he can keep his toys.