It's like Gandalf said in the first LoTR movie when Bilbo said he wished Bilbo'd killed Golum about how we can't see every possibility and end. Good point. It's like the hypothetical about going back in time and would you kill Hitler. I wouldn't. So much happened good and bad because of him that without him how things would have unfolded instead is unknown. And given how many times we came close to nuking Russia and they us since WW2, maybe we woulda. Maybe we wouldn't have a space age, modern computers, etc.
Killing another person is something we all think is the easiest thing in the world. Largely because tv fictions never show the aftermath of doing it. The nightmares, the depression, and putting yourself in thir place. So we think it's an over and done with act. It isn't. It lasts the rest of your life. And unlike other things I expect time doesn't lessen the impact.