Intelligent people are also pretty ambitious in my experience. More ambition raises the risk of failure and failing doesn’t generate the feeling of happiness. I know many smart people absolutely terrified of failure to the point they take meds for it and I know a handful who are emotionally crippled by failing at something 20 years ago. Smart people and failure do not mix.
I do not know how intelligent I am. I've taken a real IQ test, but I do not truly accept the science behind them. For N=1, the correlations do not hold true within my own life, for example. Nevertheless, I was once very ambitious, but I feel like the world has zapped it out of me. I found myself in situation after situation in which conformity and obedience were valued above all else.