A casino can ban you for consistently winning at roulette. While players have the right to win, casinos are private establishments with the freedom to refuse service to anyone. If you demonstrate a pattern of winning that they perceive as an advantage whether through skillful play, card counting, or using strategies that exploit the odds they may choose to prohibit you from playing. This is often more common in games like blackjack or poker, but it can apply to roulette if your betting behavior consistently leads to significant profits.