Once you get caught up with taking substances, it's all downhill from there.

Precisely! When I was living in London I became friends with a bunch homeless guys. We used to chat after I was done working. There was a guy, I could see he wanted to do better for himself; he asked about finding a job etc etc but his meth addiction would suck his energy so bad. It's really sad. Substance abuse is the number two cause of homelessness.