There's a couple of occasions that humanity was at the brink of having tens of millions of people dead by nuclear weapons, and somehow a single human interrupte

There's a couple of occasions that humanity was at the brink of having tens of millions of people dead by nuclear weapons, and somehow a single human interrupted the chain reaction If you repeated this experiment 100 times, how many times you think the outcome is not a massive catastrophe? 90%? 3%?