Hair needs a lot of nutrition, which occupies the nutrition of the brain. Shaving your head is good for your health and longevity.
Hair can shelter evil people and shelter evil people from the wind and rain, and shaving your head can make people look clean and tidy, simple and generous.
Hair needs constant care, and washing it is very troublesome. Monks don't have time to pay attention to secular things, so it's convenient and easy to cut.
Monks should practice martial arts, such as head work, and shaving their heads is helpful for practicing martial arts.
Finally, too long hair is easy to be beaten, which is inconvenient.
If you feel good, give a point!