Chow Yun Fat movie gamblers eat chocolate.

I suggest LZ take a look at Gambling God 3, also called Juvenile Gambling God. Starring Li Ming, Wu Zhenyu, Jordan chan, Liang Yongqi and Anita Yuen.

Dawn plays a young gambler, which can also be called the prequel of gamblers.

This movie also explains why gamblers 1 eat chocolate, turn rings and even comb their backs. In this movie, the gambler was ambushed by his master and his brain was seriously injured. As a result, he lost his taste. Only when he eats this dark chocolate, because it is the most bitter chocolate, will he feel this taste. Later it became a habit.