According to Osho, the 'secret of success' is a satire: he calls himself an utter failure, then jokes, 'The secret of success is sincerity—once you can fake that, you've got it made.' He exposes how society prizes the appearance of virtue over truth, nudging seekers to see through such games and value authenticity beyond conventional success/failure.
He’s joking that many people only pretend to be sincere to get ahead, so don’t chase fake success—be real.