Think Sports Gambling isn't making Big Money?

Between $30-40 billion is illegally wagered on Major League Baseball each year, according to CNBC. Baseball is not as big of a betting sport because of the lack of point spreads.

The FBI estimates that more than $2.5 billion is illegally wagered annually on the three-week March Madness postseason tournament each year, according to the AGA.

As much as 25 percent of illegal wagers placed on college basketball games each year comes during March Madness, according to CNBC.

Sports book operators estimate $80 million to $90 million — less than 4 percent of the illegal take — is wagered on the NCAA tournament legally through Nevada’s 216sports books, says the AGA.

One in 10 Americans play March Madness brackets according the data-processing website, wagersolutions.com. If each game in the tournament were a true toss-up, that would mean your chance of filling out a perfect tournament bracket is a mere one in two to the 63rd power, or one in nine quintillion, according to USA Today.