If a pitcher has not allowed a hit, some hold that mention of this fact jeopardizes the pitcher's continued performance of this feat. In the old days announcers and fans at baseball games took this superstition seriously and refrained from commenting on this fact. I have seen fans come to blows and even end lifelong friendships because one of them did not honor this custom. Obviously there is more at stake here than the outcome of a baseball game. Superstitions of this type extend the illusion of control.
Superstitions are also anxiety producing.
The person who breaks a mirror and imagines that bad luck will follow will not often be at ease. We note that this puts the individual at the center of the universe. Such superstitious thinking is the foundation of religious thinking. In the Judeo-Christian tradition, it is one's sinful nature which causes a just god to impose punishment and to maintain the moral balance. In the East, the idea of karma posits the same maintenance.