The 3% have either won a decent amount early and haven't averaged out yet, or they're a sharp who is carefully betting skillfully on winning bets. I don't think those people actually win too much since the platforms are always hunting to ban them. The missing money of 97% pretty much overwhelmingly ends up in the house's hands.

Even if sport bets or slot machines returned 99% that’s for one play. Play 50 times and the aggregate loss is 40%.