The guy chose to live in a box, he didn't answer an ad for living in a box. He is living at a friend's house and instead of paying him a few bucks to crash on his couch he hired a carpenter to build himself a box and made a big deal out of it by telling people.
If he'd said "I'm paying my friend $400/month to crash on his couch" no one would have batted an eye, there are countless thousands doing the same in SF, NYC, London and every other major city.