Why? This isn't a poll. It's a bet. With money on the line, the idea is that participants aren't betting on who they want to win, but on who they think will win given the polls and other factors.
But it’s a bet for something that is out of the control of the bettors, and which takes place 4 months from now, and there is much that is unknown to the bettors.
Lots of money is bet on who will win the World Series and the Superbowl, but I wouldn’t expect that the team with the biggest bets 4 months from the final are going to win.