Not at all. Have you had the pleasure of knowing racing drivers or even being one? I have.
I know the question was not aimed at me , but let me say that I know several racing drivers who are
very intelligent, bright, some of them even with university degrees.
Of course they are in low categories and they are not known around the world - I don't know any F1 drivers personally, but why would F1 drivers be any dumber? Maybe these drivers I know would have achieved more if they had been born in another country with more money. But even so, they would still be intelligent...
They usually don't have degrees, they didn't go to higher education - for pretty logical reasons - but that does not mean that they are dumb. If a brilliantly intelligent youngster decides to finish their studies at 16, they won't be less intelligent afterwards...
Maybe the racing drivers that you know are not too bright, OK, that's your own experience, but you can't say that in general.