Men sporting long hair can be read as a reflection of their personality. The compulsion has historical roots. Long hair has been notorious for being associated with rebellion and getting into trouble. Long hair on a man typically means hipster, metalhead or midlife crisis, and a sign of breaking with the norms and conventions of society.
Also, long hair on men can come with a plethora of difficulties. These include being blinded by your hair on a windy day. Also, it may interfere with a man obtaining or keeping employment, because there is a stereotype about men with long hair. It might make someone look juvenile or questionable, as long hair is often controversial on men.