I tend to think a lot of the social programs that do exist in this city (and there are many – healthy san francisco, housing subsidies, dozens of shelters, and even more food programs) don't really address the root problem that causes such a disparity. For instance, I've a number of friends who work in the tenderloin with some of those same social programs, and they're perspective is that the housing subsidies that bring people to the tenderloin only exacerbate the issues that plague it.
It's not just warm weather that draws people to SF, but a plethora of social programs that are often poorly executed, underfunded, and addressed at superficial issues and not their core causes (education, for example).
I live 4 blocks from Skid Row in downtown Los Angeles, and I feel exactly the same way. US-style homeless shelters just seem to concentrate the homeless in a geographic area, without providing them with anything they need (what most of them seem to need is access to mental health services and medications). I've heard multiple formerly incarcerated people say that staying in homeless shelters is worse than prison.
The end result seems to be a sort of outdoor insane asylum, with a bunch of privileged hipsters like me and my friends wandering from our high-end loft conversions to the latest trendy bars and restaurants.
I also feel that in many ways the property development companies are drawn to these dilapidated downtown areas with large homeless populations because it's "edgy" and the developments themselves are high-margin.
It's not just warm weather that draws people to SF, but a plethora of social programs that are often poorly executed, underfunded, and addressed at superficial issues and not their core causes (education, for example).