the.com/underachievement

means Performing below what your ability or potential suggests you're capable of.

from A straightforward 20th-century compound: 'under' (below) plus 'achievement' (from Old French 'achever,' to finish or accomplish, itself tracing to Latin 'ad caput,' to bring to a head). The word emerged alongside modern schooling and psychology, once there were tests and grades to measure potential against — you can't 'underachieve' until someone invents a benchmark for you to fall short of.