Again, you are under the spell of the assumption that if you give someone a gun, it somehow magically changes them into willing to kill. Thats a very long reach.

Look at places like college towns where there are a lot of drunk people, and fights break out. How often do you see people being killed in these regards? These are people of all sorts of mental temperaments, under the influence, managing to just punch/kick/wrestle each other without resulting to stabbing each other, despite knives being readily available.

Even more so, for the people that could be prone to violence but of sane mind, knowing that someone may be armed can be a deterrent for them actually engaging in violence, because most of those people still have a sense of self preservation, not willing to die over someone disrespecting them in some way.

And when that one outlier person who is not of sane mind and violent enough to actually use deadly force decides to go at it, its much better that if everyone else has the means to stop him.