I’ve read for years, in the Washington Post, that homeless people are mentally ill and therefore, do not choose to be homeless. And walking through DC from time to time, when I lived near there, I hardly ever saw any disabled homeless people. So, it appears that some otherwise ably-bodied, sound-minded people choose to be homeless, rather than be useful members of society.
The Haight/Stanyan bums referred to in the article are almost 100% young white male skateboard/surf/drug culture dropouts. Not a disabled veteran in sight.