IT is not wisdom if your highest goal is to avoid disappointment. An optimist also sees hope for the future and ways to make things better, which inspires and enlivens his life in ways the pessimist cannot experience, having cut himself off from his own creative powers.
Of course, these things come in many flavors. I, too, get cynical in the face of unreasoning exuberance. But nevertheless I have a strong belief in the fundamental postive impact of life striving against chaos and entropy.