Rationality > IQ

“How I got here is pretty simple in my case. It’s not IQ, I’m sure you’ll be glad to hear. The big thing is rationality. I always look at IQ and talent as representing the horsepower of the motor, but that the output–the efficiency with which that motor works–depends on rationality. A lot of people start out with 400-horsepower motors but only get a hundred horsepower of output. It’s way better to have a 200-horsepower motor and get it all into output.

So why do smart people do things that interfere with getting the output they’re entitled to? It gets into the habits and character and temperament, and behaving in a rational manner. Not getting in your own way. As I said, everybody here has the ability absolutely to do anything I do and much beyond. Some of you will, and some of you won’t. For the ones who won’t, it will be because you get in your own way, not because the world doesn’t allow you.”

– Warren Buffett in Fortune

This is a point Buffett, and other top investors, have repeatedly made throughout the years. Key attribute is temperament, not raw cognitive ability.