Interesting read(your post, haven't read the book) and the book reminds me of an idea I had of buying a small island from a weak un-allied country, making ridiculous money, and going to war for independence from said country, but where are we going to find an un-allied country nowadays lol

As for anarchy, I don't think it can exist with human nature, makes a void for authoritarians as many have said. Also, who is going to hold these private cities accountable and provide incentive not to simply devolve into states as citizens(customers) begin disagreeing? International court which will eventually set a problematic precedent? Book probably provides answers... but still lol