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...the next pick to the people who saw you pick the "winner". Now half of those people see one team, the other half see you pick the other team, and whoever saw you pick the winner thinks you've got a 100% accuracy rate over two games. You could do that for a while and then offer to sell your pick for the Superbowl. Starting with a big enough group in the beginning, this might be really lucrative.
But is it legal?
Mathematically, there are not enough people on the planet to do this with every us football game for an NFL season. Could do it for just the final games, but guessing 5 isn't impressive.
Just to do this for one team, you would need hundreds of thousands of people to get just one person. Assuming they even read your emails.