My guess is that the wealth the Seastead generated would be more of the bits/bytes kind (i.e. financial wealth, wealth represented in contracts). I can't imagine a bunch of libertarians sitting in their seastead with big warehouses full of diamonds and gold. There are more effective places to store physical assets.

A seastead is not a perfect solution to freedom. There simply is no perfect solution. It simply creates another option. It's still possible for states to seize the assets of seasteaders, but being on a seastead makes it a bit more difficult.