What makes Drucker's observation sting is that he's not warning against paralysis or caution—he's warning against *confidence itself*. We tend to think danger lies in doing nothing, but he identifies the real trap as vigorous action guided by assumptions that no longer hold. When a trusted industry player like Blockbuster insisted on the rental-store model even as streaming emerged, they weren't lazy; they were actively, decisively wrong, trapped by the logic that had worked for decades. The hardest part of changing course isn't admitting you were mistaken—it's recognizing which of your current certainties have already expired.