Smart people are just as given as anybody to the idea that happiness is about controlling outcomes, hence they are no happier. The desire to control outcomes is correlated with unhappiness because that very desire is predicated on the belief that happiness is a small target - if one would be happy with any outcome then there'd be no need to control which one eventuates. Put another way: happy people aren't the ones who win every game of chess, happy people just like playing chess.

Another aspect of this is that smart people - people good at solving well-defined problems - tend to see well-defined problems everywhere, tend to try and reduce things to well-defined problems, so that they can apply their unique gifts. This manifests as an apparent discomfort with ambiguity, which poses a problem, because comfort with, or at least an openness to, ambiguity is a prerequisite for happiness. The analytical mind is quick to label things and categorise them, including whether they are good or bad, but I find that happiness is more about refraining from applying such labels to things.

It's like with dealing with an incident. The unhappy say "the website is down, this is terrible", whereas the happy merely say "the website is down".