Good question! The outcome of the results is determined in two ways. 1) if they play an RTP machine, or 2) if they play an RNG machine. These two factors are the different algorithms used by slot developers. The first being based on the money going into the machine, the other by pure chance. A good indication can be found within the casino’s payout percentage stats. You can access this from the casino’s homepage which will inform you of the average payout. In short, players are winning from online slot machines every day and the first online casino ever has since paid out over 3 billion dollars to winners.