“Imposter Syndrome” is more than feeling like you can’t keep up. For simplicity, wiki says, “…impostor phenomenon occurs among high achievers who are unable to internalize and accept their success. They often attribute their accomplishments to luck rather than to ability, and fear that others will eventually unmask them as a fraud.” The original info I read dealt with truly successful individuals. Not your ordinary hs val or somesuch who faces competition in college.
But IS has a range, from self-effacing to the crippling doubts.