Or, the homeless are recent migrants from other areas? At least where i live, the homeless all congregate in biggest wealthiest cities, because it's easier to beg, their presence blends in more and also local communities are more atomized so they don't fight off the homeless as hard as in smaller places. I've heard a story of one homeless guy who have recently been sleeping on a bus stop near my home - he's basically travelling from one big city center to another, and stays as long as the police doesn't chase him off the area.