That's already been tried and it was a disaster. A bunch of tech billionaires tried the utopian ocean city thing in Venezuela. They lost their shirts. Docking fees are expensive, and then they have to go out into international waters every few months to dump their sewage, it costs money and you have to have a full crew to go out to sea if you have passengers.
The 10-deck ship, Victoria Majestic, is not new. It was built in 1996, but underwent renovation in 2015. Currently, it is beginning the next stage of its career. It has essentially been transformed into a residential multi-apartment building.
That's already been tried and it was a disaster. A bunch of tech billionaires tried the utopian ocean city thing in Venezuela. They lost their shirts. Docking fees are expensive, and then they have to go out into international waters every few months to dump their sewage, it costs money and you have to have a full crew to go out to sea if you have passengers.