1) Escape is the first preferred method of survival. If something bad is going down, be somewhere else.
2) Engaging the attacker is the most dangerous thing you can do, because you highlight yourself and can easily be/1
3) Neither the police nor the military has all the training needed to tell a good guy from a bad guy in a shoot out. Why should I believe that YOU do?
Look, as a member in the profession of arms, /2
Also, I've /3