I lived in San Fran back in 2012 for 6 months. I personally didn't feel unsafe; I'm a big guy and have a physical presence so I understand why others may feel unsafe.

So why did I leave?

There were a few events that really upset me. 1) I almost stepped on a shit snake some human left outside my building. 2) A homeless person stopped in front of a mother and child to urinate. 3) The weather sucked; cold and hot.

I went there for the tech scene, but it was just too dirty for me to want to live there.