Sometimes I make a comparison that's not very popular, but IMHO it makes some sense: individuals bearing guns are comparable to states which have weapons of mass destruction. No single state with such weapons has ever been military attacked. India and Pakistan used to make war, once both got nukes, both got "calm". I bet the cold war wouldn't have remained cold if it wasn't for the fact that both sides had nukes. Going to war against a state which has weapons of mass destruction is almost suicide, even if you're also a state with such weapons. Trying to assault/rob/etc somebody with a pistol on his waist is also very dangerous, potentially suicidal, even if you also have a gun (okay, okay, I know ambushes and alike remain possible but these are premeditated murders, not general for-profit aggression... it's more rare).