Albert Barnes Commentary Ecclesiastes 8:9

"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 hath power over another to his hurt." — Ecclesiastes 8:9 (ASV)

To his own hurt - Or, “to the hurt of the subject.” The case is still that of an unwise king whose command is obeyed (Ecclesiastes 8:2) even to the hurt of the wise man who obeys him.