Actually, all systems win some of the time but not all of the time. With good money management and careful bet selection you can win 10 -30% most of the time, but not always. The casino edge is the reason one can't beat the wheel in the long term with a mechanical system. But most people don't just lose the casino edge, but they lose ALL their money, because they don't have a sound money management system. Discipline is the biggest problem.