Answer:
That he believes himself her superior and that he cannot believe that anyone will give up a life for a cause are reasons why Creon underrates Antigone's courage and determination in "Antigone" by Sophocles (495 B.C.E. - 405 B.C.E.).
Specifically, Theban King Creon disdains his niece Princess Antigone for her lack of control over her convictions and feelings. He also disparages her ability to stand up under pressure when he likens her to hardened steel that snaps and to a horse or slave that is curbed or whipped. He feels that the fact if not the thought of being buried alive in a cave will be enough to make her change her mind and plead for release.