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…
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.