In my opinion the reason that intelligent people aren't happier is because we live in a world that caters to lower intelligence crowds. Think being above above average height and living in a world where everything is designed for people who are below average height.
The second reason is that society not only does not value intelligence; society values sub average intelligence. Most intelligent or even diligent people learned quickly that they will be harassed and bullied.
The last refuge of intelligence was academia, but academia does not want intelligent people. Academia wants people who will comply and play the funding game without rocking the money boat. Just ask Sabine Hossenfelder.
The second reason is that society not only does not value intelligence; society values sub average intelligence. Most intelligent or even diligent people learned quickly that they will be harassed and bullied.
The last refuge of intelligence was academia, but academia does not want intelligent people. Academia wants people who will comply and play the funding game without rocking the money boat. Just ask Sabine Hossenfelder.