He wasn't ready for the next step.

He did not put his heart in his work.

He learned nothing from his blunders.

He chose his friends among his inferiors.

He ruined his ability by half-doing things.

He never acted on his own judgment.

He did not think it worth while to learn how.

He imitated the habits of other men who could stand more than he could.

He did not learn that the best part of his salary was not in his pay envelope.

He didn't have to.