"All man's efforts are for his mouth, yet his appetite is never satisfied. What advantage has a wise man over a fool? What does a poor man gain by knowing how to conduct himself before others? Better what the eye sees than the roving of the appetite. This too is meaningless, a chasing after the wind." NIV translation
Here, Solomon describes the futility of chasing the latest and greatest thing instead of being happy with what we have. Once again, he tells us that it is like trying to catch the wind. Without this contentment that can only come from God, we are at the mercy of the next advertisement that is put in front of our face. We can chase the latest thing but, even when we get it, there will be something new that the world says we must have.
"Whatever exists has already been named, and what man is has been known; no man can contend with one who is stronger than he. The more the words, the less the meaning, and how does that profit anyone? For who knows what is good for a man in life, during the few and meaningless days he passes through like a shadow? Who can tell him what will happen under the sun after he is gone?" NIV translation
Now, we see that contentment also has to do with the fact that we cannot know and understand everything.
We have to accept the fact that God knows all things and He is in control so we don't have to worry about the future.