>To have a roommate, I suppose you have to be someone another person can stand to live with.

As someone who shared a house with housemates for 20 years, you simply have to want a roof over your head more than you dislike your troublesome roommate.

If people are homeless because they don't like living with someone else, or because they're an asshole and nobody else will live with them, I don't see that as a problem for me or society, that's a problem for them to solve.

>There has to be a market solution to homelessness

Some people need to adjust their expectations and room up in a big house with several other people to keep bills low.

Other people are mentally ill, or like to be homeless, and there's little we can do with money or housing policy to help those people.