They appeal to our bodily appetites. Quite often, even the memory of the pleasurable experiences are disturbing, even painful. Solomon realized this. Solomon had the means and power to test all kinds of pleasurable experiences. He stayed in control.
Many people lose control and become a slave to the wine, through alcoholism.
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.