Humans like to assume that people with tough lives deserve their fate. It would make then uncomfortable to think otherwise, because then they would have to accept that it could happen to them. It is very difficult to kick drug and alcohol habits and virtually impossible to "kick" mental health problems. There is a small percentage of scammers out there and they are usually easy to identify. People like that are disgusting, but the vast majority of people on the streets are in dire need of help. You see homeless people sleeping on the street with sores on their bodies in the middle of the winter. You think someone like that is going to drive home in a Mercedes?