Business world commentators sometimes wonder about it too. Why do wealthy people work crazy hours?
One reason offered is that their workplace is where they're most truly king. Respected by people working their hearts out.
Also, empowered decisionmaking offers a thrill. (And no doubt many are attracted to the elements of risk which appeal to gamblers. I remember once observing venture capitalists and thinking they resembled poker players in certain moments.)
I personally see it as similar to those people who lose themselves in computer games, particularly the strategic Sid Meier ones, where they're responsible for a civilization.
And presumably they're constantly learning things. Why don't some Nobel Prize winners just quit while they're ahead?
One doesn't have to actually create something in order to feel the thrill of creating it. For some people, it suffices to create the team which creates it. The final proof of their creativity is the fact that they own the thing which was created.
Tayssir