We humans are never happy. We might be content for a while, but that is it.

Smart people see farther than the end of their noses, and so they can effectively project out into the future, and that future always involves work and hardship, and neither of those things brings happiness.

Smart people also know that happiness is a mere moment, not a state one can be in. You have it, and then it is gone. It's like trying to grasp smoke to save it for later.