1. Who is "they"?
2. What exactly have the mayans predicted and been correct about?
2. When did the mayans predict 12-21-12 was the end of anything but a cycle on their calendar? It would be no different than making a calendar that goes up to 12-31-2999, and some civilization finding that in the future and declaring 12-31-2999 is the end of times because the calendar mysteriously ends, when really the much simpler explanation of "when that happens we roll the thousands place up one digit and start counting at 1-1-3000" makes way more sense.