purpose seems to serve as a psychological tool that soothes one by giving one a sense of organization and direction. As a convergence tool, it is, therefore, also a convenience tool. It is an answer to the question “Why do you live?” One can even make the case that it is simply a deterrent to suicide.
Purpose might just be a deeply personal narrative that we tell ourselves to fill a psychological need to matter.
Furthermore, evolutionary speaking, purpose makes a lot of sense. It allows us to continue to survive—survive harsh environmental situations and survive our own demons that may lead to suicide.