I live and work in San Francisco, there are a lot of them here and while I see a few of the same people now and again I'm asked for money by new faces every single day. It's an epidemic and I'm sick of my city and my country not taking it more seriously. But at the same time, I do not believe giving each one a dollar every time I see one is a cure for anything. I have no idea what they are spending that dollar on and it probably is not good.
It's unlikely to be food. Why? Because I have lived here long enough to know where all of the free kitchens are. They are numerous and every meal of the day can be had for free at multiple locations within the city, particularly downtown. I know they know this, and if they play dumb, I am happy to inform them anyway.
When I am asked for money, I decline, usually with a head shake. If they are aggressive and follow me I point them in the direction of the nearest shelter and/or soup kitchen. I never give out money. A few times I broke down, only to be asked by the same people over and over for years afterwards. I understand, they have no money, no job, no place to live. Except that they could. There are shelters, there are organizations that give out free toiletries and medical care and everything a person needs. USE the services.
Giving money panhandlers is not a solution to any problem and is likely supporting nasty habits you don't want to know about. If you want to be helpful, the best you can do is donate your time or money to a free kitchen, shelter, food bank, what-have-you. These services work hard to help those in need, those that work within the system. Those people sleeping on the streets instead of shelters are choosing not to work within the system (usually due to alcohol problems, but there are a variety of reasons)
And the panhandling is not even the worst. You should see what they do to the public transit system. It's a disgrace. I often have to leave trains due to the smell of some people that slip onboard past security.
BTW, speaking of wi-fi hotspots, I stayed in a hotel (in a not so great part of town) while our place was undergoing some maintenance. I was shocked and a little upset that the WiFi network of the hotel was named BurnTheHomelessToTheGround. Not even shitting. I know my attitude towards the homeless may sound cold, but all I want is to see money well spent on help, not towards drugs or alcohol. However when I see things like what this hotel was doing I see my attitude is not so extreme afterall.
Closing out a longer post than I thought, I just want to point out that being homeless and being a street person are not the same thing. The former have all my sympathy and support, having experienced it in my own family. The later can fend for themselves if they can't put some effort into cleaning up their act. I would like to see those who are too mentally ill to do so put into institutions, it's far more humane than letting them run the streets and sleep in the cold.