I'm not sure what the solution is, but many of these people are obviously extremely unhappy, and they show no sign of changing soon.
If I viewed them as part of my community, it would probably be like pouring money into a black hole. Heroin tolerance goes up very quickly, and the associated costs go up just as quickly.
if you are unable to give them money you can at least acknowledge their common humanity and treat them as a person, and not a problem to be fixed.
--edit-- HN is not letting me reply right now so to answer your question i'm putting it here: i live in the SF Bay Area, which is far more dense than Portland. I work with a lot of unhoused people. I volunteer to feed them, distribute blankets to them, and make an effort to let them see how people still care for them. Do some of them ramble incoherently? Sure, a few, but frankly, not much more than the average Fox news viewer.
Out of curiosity, do you live in a large city? Try crossing the Burnside bridge in Portland, OR every day for months and get back to me.