Conscientiousness and ambition aren’t the same thing but they are related, and conscientiousness appears to be uncorrelated or weakly negatively correlated with intelligence. With that said, I have met relatively few highly intelligent people who aren’t career-oriented; I can only guess about why.

A friend of mine is married to an intelligent, educated woman who simply doesn’t want to work. I don’t understand her - I would be bored out of my mind if I went more than a few months without a job. But I do sometimes envy my friend. He can support his family on a single income, and when he moves for work his wife has no difficulty coming with him. He can take jobs far from big cities because he doesn’t have to worry about being somewhere where she can find a job too. (Right now they live near the beach on an island in Florida.)

Meanwhile my partner and I have twice as much money as his family but we don’t even live together because I live near my job and she lives near hers. We’re both busy so we see each other once or twice a week. We aren’t just dating - we’re in a committed long-term relationship, but work comes first.