Modern English uses hubris loosely to mean “arrogance.” The Greek term is sharper. Hubris is the specific sin of forgetting your scale — believing your strength, your wit, your fortune are yours in some final way, rather than gifts on loan.
Odysseus has a hubris problem. After blinding Polyphemus, he can’t resist shouting his real name across the water — and the curse that follows costs him a decade. Polyphemus has it too, in spades: cannibalism committed in confidence that no one is coming to balance the books.
The Greeks believed the gods kept watch on hubris and corrected it ruthlessly. Modern life doesn’t do gods, but it still does correction. The form just changes. Markets crash. Bodies break. The teenager you were sure of betrays you. The pattern is older than the pantheon.