This is where the "guns kill people, not people kill people" thinking comes from.

They lose self control when they hold one. They feel power. And because they're solipsistic in their thinking, but also cannot accept blame, they have to transfer blame to an inanimate object instead.

"I would never kill someone, but when I had the gun, I did. I wouldn't have been tempted if I didn't". - No, they were always tempted to kill someone, they just didn't have an easy out.