Yes, a certain percentage of combat veterans never get over it, but among WWII veterans at least, that percentage was small. For example, author Kurt Vonnegut was one who never really got over his experience from what I understand. WWII was not at all like Korea, Vietnam, or Iraq in that the whole country was mobilized and everyone (well a large fraction) felt a part of it. In Korea, Vietnam, and Iraq the combat troops are isolated while the nation’s population goes about its normal peacetime affairs.
And for people with a legitimate need for a gun, such as carrying large amounts of cash, gun permits are available. However, I suspect a gun is on a part and a small part of the protection. Varying the times of deposit, hiring a security guard or even asking the beat cop to be around when you take the money to the night deposit drop box are others.
However, in this thread we are speaking to someone who thinks buying a gun will protect him from a camput shooter or other random act of violence. Entirely different circumstances than those you mention.