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.
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.