In the 12+ years I taught carry classes I ALWAYS emphasized the gun you carry is for your protection and the protection of people you really care about. My teaching partner (current federal LEO) and I always advised against interjecting yourself into a potential lethal force encounter unless absolutely necessary. There's basically only one good outcome...you might prevail and survive. There are an unlimited number of negative outcomes and the law of unintended consequences will always jump up and bite you in the ass when you least expect it.