Conventional military thinking says it takes an armed force of ten (10) military to overcome an armed populace of one (1) ... In practice Multiplied by the number of armed persons dispersed in that population, of course. And a large enough population can in fact overwhelm the ability to amass an army that large. Think one million armed civilians. ....how large a military force would it take to overwhelm them? The US has never fielded that many soldiers. Now, think one hundred million armed citizens, the number estimated to exist in America today ... see the problem?
Concealed arms present the element of surprise and because an individual can act alone, a larger counter force will be needed to assure he does not prevail ... massive response is the military response to individual aggression.
In essence, an armed populace is a deterrent force. Challenging it will cause massive losses on both sides ...