One relatively new term is "Speculative Architecture"... Building entire cities on speculation. China and Spain have Ghost Cities than are either nearly complete, or even complete, which are almost entirely empty. All built on speculation, but few, if any, have bought into them.
If you build it, WILL they come?
Seasteading is of that speculative nature. So far, very few bother with the necessary infrastructure. I'm working and living on a set of properties that are privately referred to as 'the lifeboat'. The goal is to be off-grid and self-sufficient, in disaster preparedness.
If they come, what will they eat? Who will be raising that food, and where is that part of the infrastructure? Shipping everything in gets expensive, fast.
If they come, there will be a need for sanitation, including water and sewage treatment. What facilities are part of the plan, and how does it get treated? Once treated, what will be done with the wastes?
There are more issues facing these concepts than tying a new high-rise into an existing grid, then upgrading the grid.
Building on spec is one thing, but, more than locations have to be factored in.