Thanks for the very interesting story! You touched on one of the biggest weaknesses I see. A failure to recognize that even at zero interest, you will need to pay back the principle. The bigger risk, I agree is maintenance.

If you're in a house you can replace the water heater or not. You can forgo updating your a/c. But in many of these buildings there is no economic wiggle room. No buffer. EVERYONE must pay for the elevator. I have a friend who sat on a condo board in NV for a bit and someone went into hysterics when a $30/month increase was discussed.

In a YT video about Chinese ghost cities they interviewed locals and asked why they didn't just occupy the buildings. They said it was too creepy and no local businesses. Unless any building is more than 50% occupied (or some number like that) it's not safe enough.

Anyway, thanks for all the corroboration! Sometimes I feel like I am missing something. I'e always wondered how there was so much urbane blight when I was young in the 1970s. I can see the conditions today that will lead to it again.