Steppenwolfe is right. I suspect the folks who tend toward the pacifist side of this discussion may never have experienced a physical confrontation with truly bad, evil people - I have. I am not espousing street justice, killing criminals on the street for property crimes where no threat or risk of violence exists - at least inasmuch as this is still a lawful society (in the old west, they did hang horse thieves and rustlers). What I am saying is there's a line to be crossed between property crime and violent crime, and for the most part bad guys are quite willing to cross that. Unless prepared, you may not be able to respond tit for tat if the bad guy cranks it up. You have to be prepared to stop the threat before you are seriously injured or killed.
In public, say walking from car to store, I'm watching what's going on around me. In a restaurant, I'll sit facing the door. Being aware can help prevent becoming a victim.
There's wolves and sheep, and there's sheep dogs - always will be. I have a good friend who won't own a gun. I've tried, can't talk him into it - his call. I've been out with the wife and she's leaned over and asked quietly, "You do have your gun with you?" Always. Not looking to shoot anyone, to suggest so is silly, I was a cop in a crime infested city for 10 years and managed to "not shoot anyone". That said, I could hardly turn away from a situation where someone needed help, not my nature.