Sports (parimutuel) gambling is different from casino gambling. There's no "house margin", rather they simply impose a fee (percentage) on the bet.
It's why on a 1:1 bet, you'd lose money, as the sportsbook tend to take something like 10%. Even though the odds are 1:1, your $1 bet would net $0.90. ($1.90, you'd get your dollar back.)
It's why on a 1:1 bet, you'd lose money, as the sportsbook tend to take something like 10%. Even though the odds are 1:1, your $1 bet would net $0.90. ($1.90, you'd get your dollar back.)