I will speak from my experience. When I was younger, I considered myself very smart, and I was pretty unhappy. As I grew, I met people much smarter than me; I stopped seeing myself as "the smart" one, and now I am pretty happy.

It's not that I became happier because I became less smart; I became happier when I stopped thinking my value was based on my intelligence, so I stopped trying to be recognized by my intellect and started working on my mental health and building healthy relationships.