Shane Parrish cites Warren Buffett on temperament being more important than IQ in business:

The 160s won’t beat the 130s at all necessarily. They may, but they do not have a big edge. The ones that have the edge are the ones who really have the temperament to look at a business, look at an industry and not care what the person next to them thinks about it, not care what they read about it in the newspaper, not care what they hear about it on the television, not listen to people who say, “This is going to happen,” or, “That’s going to happen.”

You have to come to your own conclusions, and you have to do it based on facts that are available. If you don’t have enough facts to reach a conclusion, you forget it. You go on to the next one. You have to also have the willingness to walk away from things that other people think are very simple.

A lot of people don’t have that. I don’t know why it is. I’ve been asked a lot of times whether that was something that you’re born with or something you learn. I’m not sure I know the answer. Temperament’s important.

Similarly, Dave Munger reports on research with 8th grades that found

Both IQ and self-discipline are correlated with GPA, but self-discipline is a much more important contributor: those with low self-discipline have substantially lower grades than those with low IQs, and high-discipline students have much better grades than high-IQ students.

It seems that IQ is highly overrated.