"there is no hunting like the hunting of man and those who have hunted armed men long enough and liked it, never really care for anything else thereafter." -Ernest Hemingway
He hits the nail on the head there. Man's evolution was shaped by weaponry and hunting. His first tools were weapons. The hunting party fostered communication and brotherhood amongst what otherwise would have been squabbling apes. Protein fueled the growth of larger brains. Man's most fulfilling duty is as the hunter, and if there is danger, so much the better.
But if the thrill of hunting other men is the tastiest of all, it is also perversion. To kill an animal for food is communion with the cycle of life, to shoot those perverse souls who would assault your person or property is necessary, to wound or kill a hated enemy in mutually consensual combat is perhaps not too bad. But to kill someone you have never met and likely is not such a bad fellow because the natural enemy of man, the state, has willed it so-what a horrible circumstance to find yourself in, even on the rare occasions (like WWII) when it is necessary.
Most men have courage to venture their lives if need be, yet most men seem to also have grave doubts about their physical courage and the need to "prove" it hardwired into their DNA. I am long past having anything to prove in that regard.