I guess it'd only work in places where the locals don't use AC. Otherwise it'd be a killer to run in the summer, and so you'd have capital goods rotting in a persons basement half the year.

If the user has AC for the summer, then running the AC in reverse for the winter will provide the homeowner with far more heating per joule than running a computer.

So the issue boils down to, there's not enough people living in places cold enough to make it worthwhile.

Of course, Id argue AI data centers aren't worth it full stop.