Bookmakers make their profit from the margin between the odds they give. Example. If the probability of outcome is exactly 50-50, he odds they give are 1.9 an

Bookmakers make their profit from the margin between the odds they give. Example. If the probability of outcome is exactly 50-50, he odds they give are 1.9 and 2.11 and they pocket the difference (completely fair odds without margin would be 2.0 both sides) It does not matter what the outcome is. If they balance the bets for and against perfectly, there is no risk. They generally try to balance their liability but having preferred winner can increase profits with some additional risk. If people place bets on the other side more, bookmakers move the odds to balance the bets from both sides. At some point the odds can be skewed so much that professional better can make money even after the bookmaker takes his margin. That money is taken from other betters. But if the bookmaker is not fully balanced it can come from the bookmakers pocket.