As the son of a Marine and big brother to a Lt,Col in the USAF I know what they go through to be all that they are.
Although never in the military myself I've hunted and shot 100’s of big game animals including charging grizzly.
The security guards will for the most part just protect themselves and a few will protect those they are paid to. It takes a lot to of self control to wait out a bear charge. I cannot imagine how long I'd wait to harm a fellow American. Last resort for sure.
I’ve read it is estimated that if we get hit by an EMP that 90% of the population will be dead within a year. When it comes down to people watching their family starve to death or killing people for their food, I wouldn’t bet on any civility or guilty conscience then.