Interesting read from the book “In Search of the Human Mind” by Robert Sternberg. It lists a series of points on, as you may have gathered from the title, why intelligent people fail. I’ve picked out what I find to be the most pertinent points, but do click the link at the bottom for the full list. (emphasis by me)
1. Lack of motivation. A talent is irrelevant if a person is not motivated to use it. Motivation may be external (for example, social approval) or internal (satisfaction from a job well-done, for instance). External sources tend to be transient, while internal sources tend to produce more consistent performance.
7. Inability to complete tasks. For some people nothing ever draws to a close. Perhaps it’s fear of what they would do next or fear of becoming hopelessly enmeshed in detail.
19. Lack of balance between critical, analytical thinking and creative, synthetic thinking. It is important for people to learn what kind of thinking is expected of them in each situation.
20. Too little or too much self-confidence. Lack of self-confidence can gnaw away at a person’s ability to get things done and become a self-fulfilling prophecy. Conversely, individuals with too much self-confidence may not know when to admit they are wrong or in need of self-improvement.
Sternberg, R. (1994). In search of the human mind.