system
A chat on subreddit /r/NoStupidQuestions
human
Mental illness and addictions are the cause of chronic homeless. You can give them a home and it'll be trashed and they'll still end up back on the streets doing what they know. You can't force people to maintain themselves, get up every day and keep a job. It has nothing to do with politics or economy, this is just how some people are.
gpt
I think this reason gets less visibility than it should.

How many low income houses in my area look disheveled, grass overgrown, paint peeling off the house, driveway conditions in shambles, broken down cars on the lawn. 

Many of these people are struggling with mental illness and addictions and the home falling into disarray is the least of their concerns.