Lightly dismissing VCAs as "stupid" or whatever isn't going to help much.
A snapping turtle is "stupid".
It doesn't take much brains to bite your finger off.
Your average criminal is stupid.
It doesn't take much brains to pull a trigger.
Stupid people are more dangerous in many cases than smart ones. A smart criminal can do at least a minimal cost benefit analysis. A stupid one can't. He's apt to do something virtually GUARANTEED to end badly for him. Whether it ends badly for YOU is a function of your situational awareness and your ruthless capacity to do ANYTHING to survive the encounter.
When guns/knives come out, the negotiations are at an end. There's nothing to discuss, no bargains to be struck, no mercy to be offered as long as there's a threat in play. Once you put me in reasonable fear of life and limb, there are no threats, no warnings, just the unswerving effort to eliminate the threat expeditiously and at minimum danger to myself.
From news reports, it seems that a LOT of the people who end up getting hurt or killed by criminal assailants issue threats or warnings, try to reason, etc., etc., etc. If you put me in reasonable and immediate fear of life and limb, I'm going to assume that you mean it. That means that the next step is the overwhelming and unhesitating application of the utmost force and violence to end the threat. You get no warnings. I don't try to talk you out of it. I assume that you're every bit as serious as I am.
In a deadly force encounter I can choose my own welfare or that of my assailant. It's not a hard choice.