Here's the mistake we make in high school:
We let anyone, just anyone, judge our work (and by extension, judge us.)
Sue, the airheaded but long-legged girl in Spanish class gets the right to judge our appearance.
Bill, the bitter former-poet English teacher gets the power to tell us if we're good at writing.
And on and on.
The cheerleaders are deputized as the Supreme Court of social popularity, and the gym teacher forever has dibs on whether or not we're macho enough to make it in the world. These are patterns we sign up for, and they last forever (or until we tell them to go away).
In high school, some people learn to ship, they learn to do work that matters and most of all, they learn to ignore the critics they can never possibly please. The ability to choose who judges your work–the people who will make it better, use it and reward you–is the key building block in becoming an artist in whatever you do.