Yes, I agree housing prices also affect a large number of people, but I think those are mostly the invisible homeless — ones who can scrape by couch surfing, living out of their car, etc. What I'm referring to are the visible homeless — the ones on the street harrassing people, dumping trashing, etc. I think most of those today are there because of drug addiction, with a smaller fraction because of mental illness. (And, of course, illness and addiction often overlap too.)

The reason I point these out is because I think the different groups need different solutions. Affordable housing isn't going to do anything good for something in the middle of meth psychosis. They'll just trash the place which is a complete waste of funding.