Chronically homeless often choose to be, but it's not like they had things going well for them, and just decided that freedom on the city streets would be better. They've likely been abused by cops, abused by criminals that hang around near shelters and the like, had bad experiences with trying to live at shelters, and on and on, and are probably long-time drug addicts. They can require years of help to rebuild trust in society, if not themselves.
I got off the streets with the help of an Mental Health non-profit organization who provide me with shelter and clothing along with legal services to aid me in getting disability. And of course I was granted some food stamps to get food.
I'm still a client of said organization.
