Why do parents act like crazy people went on the sidelines watching their children play a match?

Parental control, during the matches the parents need to act in a manner that doesn’t show emotion, they do not need to display exaggerated emotional expressions, like frowns, loud cheering, or the of the slapping leg in discuss or the grabbing head with both hands. This behavior causes the child to feel pressure, what he needs is support, he needs to see a calm supportive face whether they are playing well or not. This is because the parents want to win more than the child.