It's because of the cycle of happiness, people are always chasing the next goal, the next thing that will make them happy. The problem is you're supposed to also feel some kind of satisfaction from the process of going after your goal, that's what a healthy brain does. My happiness mechanisms are broken, nothing is satisfying everything just hurts, and even reaching the goal doesn't really feel good. So there's no point. I don't run on happiness anymore, I just run on guilt and self-hatred.