From all the above posts, it sounds like there’s no simple answer.
An organization I support ministers to mentally ill homeless people. They have a daunting task even though they’re in a medium-sized city. Right now, finding housing for the people they can get off the streets is a big issue. A large downtown apartment building is closing, displacing 200+ people.
The best solution is organisations like you are involved with.
As has been indicated though, the bulk of the mentally ill are treated and succesfully re enter society.
Various political agendas have a stake in making mental health advances seem a failure. Note how many attempted to claim hoards of mentally ill in the streets was a problem emerging in the twentieth century. Read up on the traumatized veterans of the civil war (or indeed any war of the past). Ask just how all those institutions came to be built, and what was done before.
My visit through lock down psych unit at a local VA hospital a few years ago was pretty emotional for me. I was there to assess some design changes they were considering for the group spaces and sleeping spaces. Residents included members of the military going back to Korean action.
I truly admire the nursing staff in this unit. Nurses less than 5 feet tall,dealing with patients towering 6’5” and they do so with no outward signs of fear, even when said patient is having a meltdown. Very calm, very professional. Very heartbreaking to see these men who are trying to cope.