I've caught a glimpse of homelessness. It was a time I was renting downtown and met the locals. A lot of them are homeless because of addiction. They do collect welfare cheques and they'll spend it all on some illegal substance they intend to sell for profit but they end up consuming most of it themselves.
I let a homeless person stay with me for awhile, and he was grateful, he'd steal things and bring it to me. He also stole bikes a lot. I told him to make it vanish and stop bringing stolen things around me.
Other times he'd be laced up on something I can't remember what it was, maybe Valium. Whatever it was it would make him treat people like shit.
Went to a bar he got us drinks, and he got into a beef with the bartender, and of course all of that reflected onto me.
He had a daughter and one time he was wasted and told me about "a friend" who molested his daughter, then tried to rationalize what this friend did.
I can't speak for all homeless people, but a part of that has to do with failure to get along with others, and continued failure to get along with others.