“Sure, but then you pay for the upkeep.”

A surprising number of “castledwellers” would probably be fine with selling it. The upkeep has driven enough of them towards bankruptcy.

Just hop on a YouTube channel for someone who bought one for a song and got hammered by failing infrastructure and 400+ year old construction techniques which are simply incompatible with modern solutions even if it was permitted to use modern solutions. Millions spent on repairs.

If you can’t afford a house, you can’t afford to upgrade a castle to meet current day living standards like running water and electricity. Also don’t forget the long ass cable you’ll need to buy to connect your remote home to the internet. Or even more expensive, also the equally long tube you’ll need to send your fecies to the sewer system. There is a reason why you don’t tend to come across some homeless dude when you’re visiting those ruins.

This is a bad idea, which gonna end be ruined by tourists.
At least suggest something better.