There are a few ways brokers make money in sports betting brokerage from spreads; most likely, the most popular by far is by charging commissions on bets. Brokers from the sports betting brokerage must see the percentage of a team's winnings. If the value of a bet is multiplied by this percentage and then divided by the total number of bets one places on this game, they can calculate what percentage their betting pool made. The better the odds of the sportsbook, the more they can charge. If you look at a sportsbook with minimal odds, they will make less commission per bet than if they had higher odds.