If everyone pitches in twelve cents, you win twelve cents per each losing player. But if two of you share a win, that's only six cents each per losing player (and there are one fewer losers).
Then you need to check your percentages in your post - it assumes that only losers pitch in to the winnings. If everyone pitches into the winnings before the game, sharing a win still gets you 50% of the winnings, regardless of how many players.