Why is it ironic that odysseus returns to his kingdom dressed as a beggar?

The irony is that Odysseus is the king of Ithaca and he set out on a journey to find riches and gold but instead he returns a poor beggar/ He lost his power as king because he gloated about it and Poseidon cast him far from home so that over the ten years it took to return he'd have nothing left, not even his supporters.