The house always enjoys a 5 percent edge at roulette. You have a decent chance of winning that first spin. And the second. And the third. But if you were to play roulette forever, the house would take away all your chips. Every casino has calculated the point at which they are guaranteed victory, and that magic number is 30,000 hands. (This is why they lure us back with lobster and luxury suites.) So if you’re winning, stop.