Nothing is more humiliating than seeing fools succeed where one has failed.

[Rien n’est humiliant comme de voir les sots réussir dans les entreprises où l’on échoue.]

Gustave Flaubert (1821-1880) French writer, novelist

Sentimental Education, Part 1, ch. 5 (1869) [tr. Baldick (1964)/Wall (2004)]
    (Source)

Alt. trans.:

• "Nothing is more humiliating than to see idiots succeed in enterprises we have failed in."
• "There is nothing so humiliating to see as blockheads succeed in undertakings in which we ourselves fail." [Ranout ed. (1922)]
• "There is nothing so humiliating as to see blockheads succeed in undertakings in which we fail." [tr. Bouvard ed. rev. (2003)]