I have a bunch of blogs because of the free service BlogSpot. I have an earned income because of an online writing service. I have social contact and an intellectual outlet because of free forums, like Hacker News. I do most of my banking online. I am paying down debt and my earned income is gradually going up.
I could really use more traffic for my websites, more customers for my resume editing service and access to decent basic housing that doesn't cost an insane amount. If I could find a simple 2 bedroom place for about $400/month, I could get off the street in the very near future. I can't seem to find that. I am in the Central Valley, not SF and I am willing to potentially move to another state, though not just ANY state. I am still finding it incredibly hard to locate a potential viable housing solution for me.
While I agree that some things add more value to the world than others, there aren't really any clear cut boundaries. Some of the people on the street are, for example, cancer survivors who are broke in part because they got treatment that saved their life (so far) but it cost a helluva lot. We really need a few more basic things solved, like universal access to basic healthcare. More cancer solutions can potentially just put more people on the street. It doesn't necessarily fix this problem.
Homelessness isn't a simple problem space to solve. There is no one thing that causes it. Some things that would help enormously:
More affordable housing, which has been in short supply for decades and getting worse.
More middle class employment options. These seem to be going the way of the dinosaur.
Single payer health care system to provide universal coverage.