Ok, fair enough. Definitely a social issue. I think part of the problem is that we overestimate the extent of what we think of as our community. I've lived in small towns, where everyone knew everyone else, and there was always a sense of trust and connection within the community. You could go to a bar and have a beer with your friends without ever thinking that someone would do (in your group, or to your group) something nefarious. At the very least, everyone knew who the bad apples were. In big cities, people can be more isolated (often, people don't even talk to their neighbours), but we still behave like we're in a connected community. When we go out to a club, we extend that same trust to those around us, even though they are an unknown in the social equation.
The social issue I see here is that there's no consensus that we're all the same tribe, and therefore should have each other's back. There are people who see others as competition at best, and prey at worst. For them, a club is not an opportunity to make social connections and strengthen the tribe; it's a feeding ground. I guess one could also turn it around and see it from the other angle. There are people who see a predator in everyone, even when it's not the case. Either way, we're losing something valuable by inhibiting the development of these kinds of social bonds.