Haha! I hadn't noticed the pattern thus far.
I think people just need a bout of fright and drama every once in a while. Plus, if we didn't have to worry about armageddon, religions would die off pretty quickly.
There has to be SOMETHING for Christianity to use for marketing, then those rumors just so happen to bleed into every other belief system in one way or another.
Truth be told, who cares. If it ends, we're obviously screwed so why waste time worrying about it. If we're bombed, we're REALLY screwed. If zombies take over, I can personally say I'm screwed because I'm slow as ♥♥♥♥. If half of us die, it'll just give people an excuse breed like rabbits and kill each other for food.
I don't know why people keep this up. It is fun to pretend, though. IMO, everyone should attempt to survive in the woods for a few months and get in touch with their primal side.