> if there was a large demand for "cheap Disneylands"
There is a large demand for cheap family entertainment, and a lot of supply.
It doesn't look a lot like “city sized theme park with exclusively licensed characters from major popular media” because...that's inherently not cheap to operate, so people trying to do it either end up being expensive, or go out of business (and the universe of defunct theme parks is a testament to the latter outcome.)
There is a large demand for cheap family entertainment, and a lot of supply.
It doesn't look a lot like “city sized theme park with exclusively licensed characters from major popular media” because...that's inherently not cheap to operate, so people trying to do it either end up being expensive, or go out of business (and the universe of defunct theme parks is a testament to the latter outcome.)