Opiates and lack of mental health care are what drives 95% of long term homelessness. There are a smattering of alcoholics as well. One of the biggest myths of homelessness is that you or I or anyone else is just a job loss away from homelessness. This is simply not true for most everyone. Most people have support networks, they haven't burned all their bridges. Almost all of the long term homeless have addiction or mental health issues or both.