To his hurt — There are some kings, who use their power tyrannically, whereby they not only oppress their people, but hurt themselves, bringing the vengeance of God upon their own heads.
Related Commentaries of Ecclesiastes 8:9
Ecclesiastes 8:9
9 All this have I seen, and applied my heart unto every work that is done under the sun: there is a time wherein one man ruleth over another to his own hurt.