There's a project called At Home/Chez Soi, run by the Mental Health Commission of Canada. The five-year project has housed about 1,000 homeless people with mental illness in cities across Canada since it began. At Home is based on the idea that people should receive housing first, instead of waiting until they're deemed ready to re-enter society. Researchers say many participants are thriving.
How much a society spends on health care has not been found to be directly related to any health outcome tested. A society that spends so much on health care that it cannot or will not spend adequately on other health-enhancing activities may actually be reducing the health of its population. If a country wants to see significant improvements in its population health, the best public policy is to eliminate poverty.