people seek equity - internal, external, individual; and make social comparisons. They, having seen many others being brilliant, succesful and all, set high targets for themselves. When they try and fail to achieve those targets, they seek to reduce dissonance (inequities) by changing either their inputs (put in less effort), or the outcomes (set lower targets), or their subject of comparison (im still better than the mediocre).
maybe it's a wise thing to do since it makes people feel better about themselves. but they stay where they are.

awareness takes you further.