Two thoughts....

First, being intelligent (as defined in the article) doesn't relate to being happy. There is nothing inherent about being intelligent that means happy.

Second, our society spends a lot of time shaping culture and people to extract value from them. For example, the focus on "more" rather than "enough". We are shaped to always desire more and never be content with what we have. Even intelligent people are shaped by this. Consider the fall in terms of people who have hobbies.

> Second, our society spends a lot of time shaping culture and people to extract value from them.

The usual trope here is that smarter people recognize this and see through the cage, leading to less overall happiness vs. "ignorance is bliss" where you don't recognize you are in a cage at all.

It's just that though, a trope. I'd argue happiness is more determined by emotional intelligence than anything, which an IQ test isn't going to measure.

Everyone wants to be happy, but nobody wants to be happy with what they have.

Second, our society spends a lot of time shaping culture and people to extract value from them.

More than that, society spends an increasing amount of time and money trying to convince people that they should be mad at each other for arbitrary reasons. I don't think this has much to do with intelligence, though.

See recently: Andrew Cuomo's racist AI-generated mayoral ad & Trump's AI generated truth post where he shits on Americans. It's hard to have a general feeling of happiness when the people with money & power in this world feel the need to go out of their way to spread their disdain for me because of how I look, what I do for a living, or the fact that I wasn't born into wealth.

> There is nothing inherent about being intelligent that means happy.

Why aren't intelligent people doing [able to do] things that make them happy? Or at least happier that someone who is less intelligent?

One would like to think that intelligence leads to making choices that bring more happiness.

If that doesn't work, various hypotheses come to mind, but I don't know how to test them.

Intelligence isn't the same thing as happiness, but it could be correlated, because if IQ does measure generalized problem-solving ability, as it seems to, then smart people could apply themselves to the problem of happiness and have more success than average in it. Then the question is "why don't they"? As you indicated, one reason may be that there's not much encouragement to, because as a society we're still in "rat race" mode.

The upshot is that society also values that we create value. Doing things that others find valuable can foster a sense of meaning and belonging.

What you touched on is desire (see: hedonistic treadmill), and while that can be inflamed by messaging in society, it transcends any given society. If we didn't have desires, we wouldn't suffer for art or create great things. Tautologically, manifesting changes like that necessitate dissatisfaction with status quo.