One early scene depicts a character being released from jail and returning to his camp in an alley in New York. All his stuff is gone. I can't tell you how common this is. Especially for the newly homeless, acquiring possessions like clothing, blankets, rudimentary cooking and eating tools, and shoes is difficult enough. Then things get dirty or wet, and most of the clothes end up in the trash. It's easier to find a charity that's giving away clothing than it is to find a way to wash what they already have.
But harder than having to throw out perfectly good stuff, the homeless have to be ever vigilant to avoid theft. Individuals can't protect their belongings, because they have to sleep at some point. People need to pair up or join a group, and that's hard, because who can they trust? How do they know? There are a lot of con men and women out there who are extremely convincing. The only way one can identify a fake is that they usually don't actually sleep on the streets. They con and steal and beg very convincingly, and then go home to a nice warm bed.
Drug addiction is addressed well in this movie. We as a society tend to dismiss drug addicts, figuring that they got themselves into this mess and we don't owe them anything. But why did they start? What crisis might push you over the edge, compelling you to do anything to escape the pain of your reality? Maybe the death of a spouse or child, or instant and unbearable debt, or getting caught at something that you're horrified of anyone finding out about you? What if you can't get health insurance and you break a bone or catch pneumonia or get cancer? Wouldn't you do whatever you could just to cover the pain for a little while?
There's a marvelous commercial (here) that shows an innovative support option for PTSD. I can't say more without ruining it. But the point is, if we have options, of course we'll take them. Homelessness, drug addiction, and hopelessness are the result of NOT having options. In this country and this time, we are the wealthiest civilization in the history of the world. How do we justify letting these desperate people suffer alone?