Monks are bald because as I read somewhere that when person is bald he looks unattractive and so no one else attract towards it. So what are other benefits to being bald either for monks or layman?
It helps to identify you socially as a monk (as does the uniform clothing), so that people know when they see you, "that person can be identified as a monk".
At the same time it helps to alter, remove or hide your personal identity, e.g. as a person with an individual appearance such as hair color and hair style.
I suppose another practical benefit is that it's also clean and cool (an opposite extreme, for some non-Buddhist sramanas, was to not touch or cut their hair at all, so that it became long and matted).
So far as I know the practice pre-dates Buddhism: MN 26 says,
So, at a later time, while still young, a black-haired young man endowed with the blessings of youth in the first stage of life — and while my parents, unwilling, were crying with tears streaming down their faces — I shaved off my hair & beard, put on the ochre robe and went forth from the home life into homelessness.
-For monks, having to be bald helps weed out those who are too committed to sensual desire and are not ready to be a monastic.
-Having no hair is one less thing to cling to.
-Being bald means less parasites and less potential harm to the parasites.
-No hair is easier to handle and clean.
-Being bald can help one identity with Buddhism and other Buddhists or truth seekers.
That's pretty much it right there. How hair is styled, its fullness, color, length, and anything else about it, can cause vanity, envy, and attachment. It's the reason that the haircare industry is estimated to exceed 85 billion this year: https://www.statista.com/statistics/254608/global-hair-care-market-size/
From a personal note, it's also very easy to take care of. Just make sure you put sunscreen up there if you spend any time outdoors. ;)