Great article on it.

Billion Dollar Bracket Challenge: Why it’s a bad idea to enter Warren Buffett’s March Madness contest.
"There is a chance, but the chance is so vanishingly small that it’s actually more rational to say there’s no chance. As Yahoo and Quicken note in the fine print of their

rules page: “odds of winning the Grand Prize are 1:9,223,372,036,854,775,808.” That’s 1 in 9 quintillion and change."

Another way to think about it: If all 317 million people in the U.S. filled out a bracket at random, you could run the contest for 290 million years, and there’d still be a 99 percent chance that no one had ever won.

Jeff Bergen, a math professor at DePaul University,

derived a more realistic calculation that takes basketball knowledge into account. If you know the sport pretty well, he concludes, your chances of picking perfectly are more like 1 in 128 billion.

Still not so hot. As Bergen explained, that would mean you’d need to fill out about 90 billion brackets before you even had a 50-50 chance to win.

ESPN has been running a large-scale bracket contest for 13 years. Nobody has ever come close to perfection, the sports network’s John Diver

told CNN in January. Only one person in the last seven years managed to pick just the first-round winners correctly.