He might be sane now, but will he always be? How about each of the next 100 leaders? The terrifying thing is that it only takes one crazy/confused/suicidal lead

He might be sane now, but will he always be? How about each of the next 100 leaders? The terrifying thing is that it only takes one crazy/confused/suicidal leader to obliterate humanity. The risk in any given year is usually low, but everyone knows how small chances compound over time.