Explain to me why my attitude is wrong.

[ddubois]

Maybe move this to politics?

You have a store front. A man comes in, sticks a gun in your face, and demands money. You give it to him, and then as he turns and runs for the door, you reach under your counter, grab your gun, and shoot him. He dies.

Your action seems perfectly acceptable to me. Explain to me I am wrong, why this is immoral, and why the world is a better place because this is illegal and with your subsequent imprisonment.