Y2K, Climate Change (global cooling, global warming), ozone layer, Russians, Muslims, to name a few. Now go ahead and tell me why these don't count.

Almost no one believed Y2K would kill everyone, or even a significant (>50%) percentage of the population. Beyond a few people talking about a Nostradamus prophecy or some such, people maybe were concerned that airplanes would fall out of the sky and elevators would plummet.