The Four Horsemen are BORED.
Sitting around for eternity waiting for The Call can get rather dull. Especially when Three of the Four notice that their brother, Death, gets to come and go as he pleases. To add insult to injury, when they finally make it to Earth, they find that they may not even be needed afterall. They aren't happy. And so,
The End of the World will be happening a little bit...early...