I can't understand why you'd think that, first of all.
The Mayan's had some good knowledge of the position and movements of stars in the sky, sure, and incredible considering how little they apparently knew about much else. But they also didn't know that the planets moved around the sun in elliptic orbits. Or what stars were. Or that gravity was a thing. Modern astronomers exceed their knowledge on how the planets and stars behave in the same way string theory exceeds doing addition on your fingers.
But even if I granted that the Mayan's knew incredible mysteries about space that NASA can't fathom with observation satellites in space, even if I granted that a prophecy they made about the end of the world would be scientifically grounded... the Mayans never predicted that the world was going to end at the end of their calendar. That the world ends on the 21st of December 2012 is not a Mayan prophecy, it is a Western prophecy cobbled together by misreading their calendar and putting an emphasis on the fact that it ends somewhere that would have been unknown to the Mayans themselves.
But what I really can't understand, is people who are convinced that the world is going to end in a few days, and are going and stocking up on freeze-dried food and toilet paper.
It's going to be the end of the world. You're not going to be able to use it.
Buying those things makes good sense if you think the economy is going to collapse, or if you think there's going to be a nuclear war, or an alien invasion, or if you think (against all logic) zombies will take over the country.
But if you think the earth and the cosmos will come to finality on a specific date, making plans for anything beyond that date is profoundly silly.
In contrast, I am reminded of the most recent previous doomsday scare, involving Harold Camping and his irresponsible handling of the Bible. He managed to convince a fair number of people that the world was coming to an end on October 21, 2011.
In preparation for this, the people who believed his prophecies began selling everything they owned and donating it all to a billboard campaign to alert as many people as possible. Some quit their jobs and just traveled around prophesying in street corners, trying to bring people to Jesus before the end took them all. Some took out loans that they knew they'd never be able to pay back (and never expected to pay back) to get SUVs and trucks to hail billboard-ads around.
They didn't stock up on food, because the world was going to end and they'd never be able to eat it. They didn't stock up on fuel for generators, because the world was going to end and they'd never need to use it. They didn't build underground bunkers, because the world was going to end and they wouldn't be alive anymore.
While those actions came to naught, if the world was going to end and we knew it was, that is how people should act.
I think this was highlighted no where more clearly than someone asking Harold Camping if he could have his car on Oct 22, the day after the world ends, since Camping wouldn't need it. And Camping responded that "it wasn't going to be business as usual" on the 22nd. There weren't going to be cars or roads to drive them on, so planning for that was futile. Camping was convinced the man addressing him was not going to need a car, or a house, or money, because he and all other life forms on the planet would be dead and judged on the 22nd.
I don't know how we developed this weird idea that we need to stock up in bunkers with food and ammunition so that after the apocalypse we can survive. There is no surviving the Apocalypse, by definition. There is no "post-Apocalypse", except in one of two afterlives.
"The ground of a certain rich man produced a good crop. He thought to himself, 'What shall I do? I have no place to store my crops.' Then he said, 'This is what I'll do. I will tear down my barns and build bigger ones, and there I will store all my grain and my goods. And I'll say to myself, "You have plenty of good things laid up for many years. Take life easy; eat, drink and be merry."' But God said to him, 'You fool! This very night your life will be demanded from you. Then who will get what you have prepared for yourself?' This is how it will be with anyone who stores up things for himself but is not rich toward God ." - Jesus, Luke 12:16-21If Doomsday is coming, then quit your job, hug your family, see as much of the world with them as you can, empty out your savings account and your children's college funds and give it all to charity and public awareness of the disaster, and tell as many people as you can so that we can all prepare to meet our Maker.
Otherwise, if you're not willing to do that, then you don't actually believe the world is going to end, so please stop talking about it. Thanks.