Have you ever tried bringing a smile on someone's face? I have and believe me there's nothing in this world that gives more satisfaction than this. Be it giving a rikshawwala an extra 20 bucks because he had asked for little less than others being new to the city, or helping a small girl getting that flower she is trying to reach from past few min, or feeding a small hungry child a parantha that you would have thrown otherwise.
How can you derive satisfaction from harming others, killing others. Nothing can justify the tears of a mother who has lost her small child in front of her eyes, the tears of a new bride who lost her husband, the tears of an old man who lost his only hope.
Just try bringing smile to someone's face once and see if that brings more satisfaction or harming people for some reason unknown.