Its literally a case of fiction controlling reality. A lot of "badass" women in movies had it, so women in real life thought it would make them look badass and rebellious and all that other shit women love to do because they are grown children. That's why you always see it on girls who are trying to "break the norm" despite it being so common.

Men adopted it partly because women did and partly because niggers also do those side-shave things in some form and they wanted to ape it but not exactly to dodge cultural appropriation cries.

As always, its a trend from over consumption of media and trying to emulate things that look "good" there.