Regarding the incident in Chicago where an innocent 16-year-old was beaten to death: My prayers and thoughts are with his family.
I have taught my students to always be aware of their surroundings. Trouble will sometimes find you despite all of your efforts to avoid it. Better to not help it (Trouble) by frequenting areas with people who behave stupidly. Let me be clear: I am NOT blaming the victim in this case. Sometimes bad things happen through no fault of our own. Many of us have been careless at one time or other with respect to our situational awareness.
Mobs are by definition chaotic. Bar brawls = same thing. Even if you were not involved in what "started it" a bar fight spill-over effect can happen. Some idiot chooses to use the chaos of the situation to take a shot at someone, anyone, and for any reason or no reason. Do not attempt to apply logical to the illogical.
Mr. Myagi said, "Best defense--no be there."
Oh, and be prepared.
Dalton said, "Those looking for trouble are not much of a problem to someone ready for them."