Why are there minimum and maximum numbers of contestants in certain contests?
By law, the entry fee must be fixed beforehand. If there are an insufficient number of entrants to reach the minimum number of entrants for that contest, the contest will be cancelled. Heads Up contests always require two entrants. If there are less, the contest will be cancelled. Some contests, including solo contests, heads up contests, and league contests, have a maximum number of entrants to fix the prize pool to entry fee ratio.