The results, though he completed his great projects, were disappointing. Solomon's negative verdict supercedes his positive one. And so, Solomon experienced the same emptiness, whether he pursued frivolous pleasure, or pleasure through work on great projects. This is the way of pleasure. It is unfulfilling.
Pleasure is for the moment, at the cost of the future.
We enjoy the moment of pleasure, but are left thirsty for more. When the moment is gone, all that is left is weariness and frustration. Pleasure promises more than it can produce. Its advertising agency is better than its manufacturing department. In and of themselves, there is nothing wrong with pleasurable experiences.