So, why does intelligence lead to happiness? Maybe it's because intelligence gives you a better understanding of the world, so you can navigate and solve problems more easily.
The question remains whether more intelligence is better or not. Maybe the sweet spot of intelligence has a different meaning for each person.
Imagine having an IQ pill that can increase your intelligence. Would it make your life better or worse? It's a fascinating question.
There's virtually no research based on a neuroscience approach to solving the problem of increasing intelligence.