From what I understand, the prophesy merely describes a transition from “One World Age to the Next”. No horrible end, just a demarcation in time. Supposedly everything was divided into “Galactic Days”; one galactic day = 25,625 years and is divided into five cycles of 5,125 years.
Why? I don’t know. It was somehow related to the Mayan understanding of the Solar System, and some sort of “synchronization” between our sun and the central galaxy.

But, you really can’t blame Hollywood for making a movie out of it, and for taking the “End of days” theory. Transition is so-o boring.