Dopamine is responsible for motivation and drive, not just reward. The release of dopamine can be achieved through positive thoughts, certain drugs, and supplements, but when stimulated excessively by drugs such as cocaine and methamphetamine, it can lead to addiction and a decrease in baseline happiness.
Our neurochemical systems, including adrenaline, cortisol, dopamine, and epinephrine, were not designed to help us build Fortune 500 companies, but rather to be generic and adaptable depending on our circumstances, such as foraging for food or searching for a mate.