What the majority of people are concerned about is the chances of violent crime that is likely to affect them. Yes, there might be 80 gang murders a year in Atlanta but a $100k+ income working professional in downtown has a very different threat model than a gang member in some of the worst neighborhoods of the city.
I think the reason SF gets so much negative attention is because the threat to "average people" (realistically, above average income people) is anecdotally quite high in SF, even in "nice" areas of the city where affluent people frequent.