Il n'y a point de sots si incommodes que ceux qui ont de l'esprit.
No fools so wearisome as those who have some wit.
François de La Rochefoucauld, Maximes (1665–1678), No. 451. Translation: J. W. Willis Bund and J. Hain Friswell (1871).
Variant: No fools are so difficult to manage as those with some brains.