Wagering requirements prevent players from withdrawing the bonus money immediately after receiving it. Before the bonus money can be withdrawn the player must wager a certain amount of money on unrestricted games. The wagering can be spread out over many bets. To meet a $2000 wagering requirement, a player could make 1000 $2 bets on blackjack, provided blackjack is not a restricted game. Games like blackjack and video poker have a low house advantage. The house advantage for blackjack is ~0.5%. So in the example above, by playing $2000 worth of blackjack with a house advantage of 0.5%, a player is, expected to lose $10 in total. But the expected value is an average value and may be less than the actual value. Risk of ruin is an important topic that comes into play.
Assuming that the player only loses an amount close to the expected loss, and the bonus awarded to the player after meeting this wagering requirement is greater than $10 then the player profits. The process is mathematically calculated. Bad luck could cause a player to lose more than $10 playing blackjack in this situation. The run of luck is subject to variance and follows a normal distribution. By taking advantage of 'free' bet promotions, users can back the event, and then lay the event on a betting exchange, at similar or same odds, thus ensuring that their 'free' bet is not a bet at all, instead more like a financial trade. No matter the outcome, it is possible to calculate both the possible outcomes before the sporting event has started. By inputting the odds, the bet calculator then tells you what amount to bet, to ensure that whether the bet wins or loses, the return are the same.