"Why Are Some People So Concerned About The End Of The World?"
We'll, a lot of our current narratives involve the fall of giants - Dinosaurs, Rome, Empire etc. As we're constantly made aware that the "human race" as a group is dominant top-dog, maybe we're all showing a little self awareness? Or am I being too kind?
The major narrative of popular environmental science follows this kind of apocalyptic trajectory. Maybe it's rubbing off on us.
Also, there's a difference between the end of the world and dying. The end of the world might be torture, where as most our ideas of dying currently involve something like the sound of a party-popper going of and then a quick fade to black. :)