In considering the issue of  the Dynamics of Intelligence (Myers, pp405-410), Robert Sternberg (1986) has asked "Why do intelligent People Fail?" He gives the following answers:
1. Lack of Motivation
2. Lack of Impulse Control
3. Lack of Perseverance and Perseveration
4. Using the wrong abilities
5. Inability to complete tasks
6. Lack of Product Orientation
7. Inability to translate thought into action
8. Failure to Initiate
9. Fear of Failure
10. Procrastination
11. Misattribution of Blame
12. Excessive Self-Pity
13. Excessive Dependency
14. Wallowing in Personal Difficulties
15. Distractability and Lack of Concentration
16. Spreading oneself too thin or too thick
17. Inability to Delay Gratification
18. Inability to See the Forest for the Trees
19. Lack of Balance between 
Critical, Analytical Thinking and Creative , Synthetic Thinking

20. Too Little or too Much Self-Confidence

Sternberg, R. (1986). Intelligence applied. New York: Harcourt Brace Javonovich.