There's just no good answer and I go through similar emotions frequently. Every time I see a $1,000 dollar bike being ridden by someone who it clearly doesn't fit...and using regular shoes on clipless pedals, I want to impersonate batman, but that's a fantasy, not reality. Calling the police is nearly sure to be useless; in Philadelphia if you aren't dead, or if it didn't happen to a cop, it doesn't matter. There's a pawn shop I walk by regularly that bought a clearly stolen bike and, when caught with the stolen bike were entitled to their payment back from the victim. Apparently they have immunity from certain laws that everyone else here lives under. Every day I walk by I want to break a window (and if I were 24 I probably would). All you can really do is remember that there are a lot of schmucks and slime balls and try your hardest to avoid being around them. If there is a good answer for the homeless and addiction, I don't know what it is.