Just for the sake of the argument, I suggest you consider the cold war. It was a very large scale version of the boat scene. You had two parties armed with the ability to destroy the other. Both parties understood that the other party was considering their destruction. Yet, here we are, still alive. It isn't as crazy as it sounds to think that there are those who would hesitate. Ethics may not do much, but many people still have a moral code. I appreciate your skepticism though. I'd say six times out of ten, people would destroy the other party without hesitation, but at the same time it is poor logic to assume that 100% of the time, the outcome will result in people automatically forsaking the other party.