You are unaware of Horiuchi's MOS at the FBI? He was a sniper, nothing more or less. He loved to kill.
Although I'm certain that Horiuchi himself fits the description of psycho killer, please don't lump all snipers in there with him. Else you risk besmirching the reputations and souls of a lot of brave soldiers who ventured deep into enemy territory to excise a cancer with a single surgical shot. Folks like the legendary Carlos Hathcock. Most sniper's don't love to kill, but they're good at their job and take pride in doing something to tangibly defend this country in a way very few can do. They're SHEEPDOGS, hunting wolves to keep the flock safe.