See https://www.latimes.com/california/story/2019-10-07/homeless...
Many homeless don't have mental health and substance abuse issues, but are just forced out of their homes on debt, etc. And of course some develop mental health (and sometimes substance abuse issues) after living homeless.
Assuming that is an affordable solution (it's not), we will then simply end up with destroyed houses.
In fact in seattle, King County, sued PURDUE PHARMA, L.P.; PURDUE PHARMA, INC.; THE PURDUE FREDERICK COMPANY, INC.; ENDO HEALTH SOLUTIONS INC.; ENDO PHARMACEUTICALS, INC.; JANSSEN PHARMACEUTICALS, INC.; JOHNSON & JOHNSON; SEATTLE PAIN CENTER MEDICAL CORPORATION d/b/a SEATTLE PAIN CENTER; FRANK D. LI; SALES REPRESENTATIVES JOHN.
This is where it starts, as much as it would be great to turn this into a debate about the US military these pharmaceutical companies and Holy Prestigious Doctors are far and away the major cause of these issues.
[1] http://nchv.org/index.php/news/media/background_and_statisti...