I can't give you an actual answer to that. I don't know of any to date. I'd be curious, and I'd like to do some research on that.
Some people have never owned a house. They've only ever lived on their boat; they're live-aboards. I'm going to say that these folks here who are squatting are just like the folks we see on the streets living in tents. They were once housed and then became unhoused. For them, moving onto a boat, whether it was given to them or whether they just decided that this boat had been abandoned there for such an amount of time and they could move onto it.... It's a good question that I unfortunately don't have the answer to.