Why do we loose hair if we always wear hats and caps ?

It depends on the person’s hair and the type of hat they wear. If the hat is always pulling on or rubbing at the hair it can cause it to come loose and the person will lose more hair than normal.

If the hat is particularly tight, it could break the hair follicles, and cause bald batches (also called friction alopecia). ... It's also possible that “wearing a tight hat speeds up the progression of baldness by reducing the optimal blood and air supply to the follicles.”