Do you have to find out/ prove something to get a PhD?
Getting a PhD almost always requires one to have some original contribution to your field. That result doesn't always have to be an earth shattering proof of something completely original. Your work can build upon existing work, or draw connections between a variety of different topics that no one has noticed yet, or even just suggest that there is a problem that nobody has considered yet. The point is that there has to be something unique, and original that counts as your contribution to the body of knowledge. That isn't easy to do certainly, but it isn't impossible for normal people to accomplish through lots of time and hard work either.