People live their whole lives in these sorts of neighborhoods without ever personally being assaulted, robbed or burglarized.

I know this is a topic that tends to bring out hysteria instead of rational assessment of probability but seriously, it's not as bad as people think. That said, the upper class crowd should feel free to not move in. The added pressure from gentrification would probably not make things better if SF is any indication.

My point here is that you can live cheaply in these neighborhoods and while there are trade-offs the trad-off is not the "living in a war zone" that many people would have you believe.