Man i love the idea of this sort of thing. Surviving in civilization but in a more natural/primal manner. Ive heard it be called urban camping or stealth camping. A youtuber i watch who also scratches that itch is steve wallis, who recently made a little fort under an overpass, compelte with little tv and stove and stuff

I think its a deep disillusionment with society that makes this attractive. Same reason i fantasize about having an isolated homestead, or being stranded on an island and thriving, or why i like being up at night when everyone else is asleep. A simple escape from society and its slings and arrows