I feel like you’re inching towards the paradox of learning, a very important problem for especially ancient Philosophy. —You could think of it from a teacher’s perspective:
Some of the students don’t need your help; and the remainder can’t or won’t benefit from it.
So why become a teacher? Indeed this problem cuts to the very possibility of learning anything at all. How could you learn something if don’t already know about it; how would you know where to “look”? This is in a way a bootstrapping problem.
For Plato, the solution has to do with reminiscence; all apparent learning is remembering, owing to a kind of transcendent Memory oriented towards a “past beyond the past”. Hence: you knew all this before birth; what you perceive as learning is only remembering.