Who's to say there will never be anything to be gained? Scott could show up any time. Or Derek could show up from when he was the Alpha. Or another Alpha could show up from another pack. Or from another universe and you could try your hand at that. Or you could get bored. There are so many things that could make you want to kill again. And that's without considering that maybe you just got a taste for it.
I'm not Scott. I don't assume the best of everyone. I don't give second and third and fourth chances. Do what you want here, but if you ever become a threat to the people I care about again, I'll end you.