The answer to this question also depends on how you define success. It seems like most people are thinking of it in terms of earning achievement. I have a couple of other ways of thinking about it: happiness and status achievement.
One does not need money of much of anything else to be happy. All happiness requires is that you make yourself happy doing whatever it is you are doing. If you’re happy, what is the motivation to change? I guess, for most people, happiness is a moving target, and change is always a condition of future happiness, but again, that doesn’t have to have anything to do with money.
Similarly, there are other ways of achieving status besides making a lot of money. People do important altruistic work or art work, and may not make a lot of money at all, but are the kind of people that everyone wants to be around, and everyone admires and respects. Money may be a generally good way of measuring status, but it has many flaws. It also changes the general notion of what people think success means. Success starts to become seen as something that is measurable, rather than intuitive or personal.
IQ measurement is something that is culturally specific. That is, it measures one’s ability to answer questions that the questioners think are important. What is important depends on what the society thinks is important. In Western cultures, people value money and the best way to make money is to know how to do math and reading and logic and analysis well.
Logic and analysis may be universals across cultures, but math and reading are not. Intuition may be more important for success in some cultures. An ability to create compelling stories, or to make compelling movies may help one be successful. I don’t think IQ tests can measure anything related to these tasks. Can it measure creativity? I doubt it. Is traditional IQ related to creativity? I don’t know.
IQ, I believe, is a measure of what you know that is important within a culture. As such, one would expect it to be predictive of a potential for accomplishing things the culture values. However, it doesn’t measure drive or aggressiveness or inventiveness, and all these things are part of a person’s potential for success within a culture.
One’s intellectual capabilities are only part of a person, and only partially related to achievement of culturally specific success. I don’t know how much they are related to success. I think that IQ measures how well you can do on academic things. How well you can read and do math and be logical and analyze things.
If you need something analyzed, I’d take it to a person with high IQ. I’d want that person also to be responsive and motivated to help me. Those are EQ things, I guess. IQ doesn’t measure EQ, so it is still a poor approximation of a person’s potential or ability to accomplish anything, except, perhaps, study. But we know a lot of slackers and druggies who have very high IQs.
You might say that a person with high IQ might be interesting to talk to. Then again, they might only want to talk about one thing, or have poor social skills, or never listen. So, in the end, all IQ tells you for sure, is that the person knows how to take IQ tests, and is motivated to do well on them.