Because there has not yet been a potential disaster that bad, or because more than one person was important to the disaster being averted?
We do have enough nuclear weapons to kill all humans, and there is some chance of them all simultaneously being detonated—so I would not endorse the first clause. The second clause is not the only alternative, though: consider also the case where the probability of disaster per unit time is small.
We do have enough nuclear weapons to kill all humans
It’s not clear this is the case, actually, despite it being a part of the common culture. Nuclear winter style scenarios are possible, but even then it’s not clear that all humans would die.
We do have enough nuclear weapons to kill all humans, and there is some chance of them all simultaneously being detonated—so I would not endorse the first clause. The second clause is not the only alternative, though: consider also the case where the probability of disaster per unit time is small.
It’s not clear this is the case, actually, despite it being a part of the common culture. Nuclear winter style scenarios are possible, but even then it’s not clear that all humans would die.
OK. I was really just trying to say that I agreed that there was some chance of a rapid violent end of humanity.
Nuclear winter → reglaciation → meteorite strike—or whatever scenario you prefer.