Most homeless people who are suffering from mental illness are not interested in therapy or medication or they would be seeking it out. Have you ever talked to any homeless people? Therapy consists primarily of long meetings with both a counselor or a group. It's not fun and it's not easy, and of course in group therapy you may hear some people's stories over and over. Medication will not make them feel better, just different, and sometimes unpleasantly so. A cigarette and a bottle of malt liquor will make them feel better, right now.

I'm not blaming anyone for being mentally ill. I've worked in a locked behavioral health facility, so I know what the score is. No one wants to be locked up, and a regime of medication or a detox from drugs and alcohol does't work, unless they are locked up. No matter how nice a facility is, being locked inside makes it no different than jail, and you are locked up with insane people.

It is really easy to see how the symptoms of BPD would cause someone to end up on the street. If someone is making themselves really hard to be around day after day, eventually the people around them are not going to give a crap about the medical side of it, since they have to live their own lives without dealing with someone who is treating them like an asshole every second.