Why we suffer?

"We suffer for the simple reason that suffering is biologically useful. It is nature’s preferred agent for inspiring change. We have evolved to always live with a certain degree of dissatisfaction and insecurity, because it’s the mildly dissatisfied and insecure creature that’s going to do the most work to innovate and survive. We are wired to become dissatisfied with whatever we have and satisfied by only what we do not have. This constant dissatisfaction has kept our species fighting and striving, building and conquering. So no—our own pain and misery aren’t a bug of human evolution; they’re a feature."