Just tax em, no need to seize anything. People aren't going to stay invested in things that are clearly going to lose them money on an ongoing basis. You can

Just tax em, no need to seize anything. People aren't going to stay invested in things that are clearly going to lose them money on an ongoing basis. You can even phase it in over time. That said, I think working on creating more housing is a better idea than making a bunch of rules about who can own existing housing.