I think that the answer is obvious: remove an incentive to the crime, i.e. stop disarming people capable of defending themselves!
You can arm all the people you want and the mass killings are not going to stop. The people who do them seem to be willing to kill themselves in the first place (i.e., the death of the perpetrator is of no concern to themselves). They can do a lot of killing very quickly before they kill themselves and/or are killed. That's just the way it is.
No amount of arming everyone is going to stop these kinds of mass killings.
But, as I said, I don't have a problem with carrying to defend yourself. I'm just saying that this "methodology" is not going to stop these kinds of mass killings.
You were saying ...
No amount of arming everyone is going to stop these kinds of mass killings.
Fundamentally wrong. If the perp want to be killed - it can be done swiftly by armed victims, therefore avoiding MASS casualties.