Grow food? Hunt? What are you on about, you just panhandle and buy stale bread and such from supermarkets or go to charity sponsored shit. The problem could be warmth and shelter, often landlords try to rape young people they can throw out into the streets and since the homeless are considered schizos with nobody to tell it's seen as rather riskless to just rob them up for their panhandled cash. Though the police also has big trouble finding someone without an address, by the time you are ambitious enough to be a criminal yourself you are unlikely to still be homeless.