Although there are very smart people, such as Bill Gates, Steve Jobs, and others, who are brilliant and successful, success often eludes lots of people with high IQs. Why is this?
Psychologist Robert Sternberg has discussed the concept of "successful intelligence." Having a high IQ is not enough. Successful people need to recognize and capitalize on their strengths, but also have to correct or compensate for their weaknesses. For example, brilliant leaders have failed because of their inability to admit to a mistake and change a course of action, or because they are unable to trust others and ask for help or delegate tasks to others.
IQ is not enough because two other forms of intelligence, social intelligence and emotional intelligence, are also important for success. Think of the popular TV show, The Big Bang Theory, about brilliant scientists, with high IQs but almost no social intelligence/social skills, and little awareness of their own odd behaviors. Likewise, brilliant people are often undone by a lack of emotional intelligence, as they let their passions or inability to control their emotional outbursts be their undoing.
Finally, Sternberg suggests that in many cases it is creative intelligence that makes people successful: the ability to invent or create something new by thinking "outside the box," or the ability to take a good idea and turn it into a great one.