How do you know that? Research usually suggests that the most important factor in homelessness is unaffordable housing.
Even if you give them free housing, they'll mess it up somehow. They can't hold down a job. They don't take care of the home. They'll abuse the home until it's unlivable.
If it's truly unaffordable housing, why the hell are they in SF? Go to somewhere that is 1/4th the price. Plenty of places in the US.
Source: Lived in SF for 20+ years.
Of course all the research (admittedly limited, but there is no research showing this “well known fact”) this well know fact is just false.
Not hard, not complicated.