>In the musicians category I wouldn't be surprised if the best musicians were also smarter than the general population.

I seriously doubt that, actually. Are they more musically gifted? Sure. Smarter overall? I'm not so sure. It would be an interesting study.

I imagine the ones who are both successful musicians and businesspeople (i.e., they run the business themselves mostly, in addition to being musicians) probably are very intelligent, because that requires a broad range of skills. The ones who are just good at playing an instrument or singing some lyrics that someone else wrote? Not so much.