Because then others will be left alive to ask questions about my decision and be a pest. While i continue to live, i don't want to take responsibility over anyone's life or death, especially a human's life. Killing individuals while others live creates fear in others and that can cause all sorts of problem.

Unless the whole world can go boom in an instant, I'm not bothering with other's life or death. In the case of pressing a button,I won't care for anyone else's consent because I know there will be no one left to suffer from it in any way. While we are alive, people can protest that pressing a button will violate many people's desire to keep living but collectively we came into existence without our knowledge and will go out even if many don't want it.