All joking aside, I’ve known two snipers in my time, and they’re both more than a little cracked. I’m starting to think it’s a job requirement.
Perhaps a line from Breaker Morant sums it up best: "The fact of the matter is that war changes men's natures. The barbarities of war are seldom committed by abnormal men. The tragedy of war is that these horrors are committed by normal men in abnormal situations. Situations in which the ebb and flow of everyday life have departed and have been replaced by a constant round of fear and anger, blood and death."