Why doesn't Odysseus tell his men of Circe's last prophecy?

Odysseus does not share Circe's last prophecy with his men to prevent them from succumbing to fear and despair. He understands that the knowledge of the dangers ahead, particularly the threat of facing the Sirens and Scylla, could demoralize them and jeopardize their journey home. By keeping this information to himself, he aims to maintain their courage and resolve, ensuring they remain focused on their goal of returning to Ithaca.