The superficial sense of Ecclesiastes is often mysterious, because Solomon speaks in illustrations fifty percent of the time. He does not tell you it is an illustration; you have to identify it.
Who behaves like that? We do spiritually. We have not taken an oath, but we are obliged by a higher principle: he created us. Our commission is to live life God’s way, to thank him, to accept his authority over us, to obey him. But instead he sends us out into life, and we ignore him and do as we like. Each one of us must appear before God, our heavenly King to give an account for this life. Is it a small matter to make vows to God and not to perform them? Yet we are under obligation to live for God and to love him with all our heart, soul, mind and strength. This is his commandment to every one of us. We may ask, how could anyone be so foolish as to ignore their responsibilities to an earthly king, but we have all done the same when it comes to our heavenly King. Do we realise we have a living God? He has absolute disposal of our lives. But we can act as such fools; we will be cast from his presence. So Solomon shows us the foolishness of our rebellious ways.