The piece of paper is just the evidence that you've been through a journey successfully. What you're really paying for is access to the environment that facilitates that journey.
The journey is essentially transitioning from a system which is pricipally about executing diligently on well-defined instructions, to one which is about reaching more broadly defined and often even self-selected goals by whatever means you choose.
Obviously aspects overlap, the changes come in steadily over the years of a degree, and even in the most ideal case it's still basically just practice, but the journey is supposed to develop the higher order skills that at that age you are ready to develop, and must develop to succeed 'in the wild' so to speak.
Absolutely 100% one of those higher order skills, indeed maybe the most important, is being able to self-teach whatever necessary to fill in gaps in order to do something interesting, that won't be provided for you or made easy for you in any way. You have to figure it out on your own. Just as you will have to in more or less every single challenge you encounter in the world after university.
So again, the environment in which you develop those skills (along with so many other benefits) is what you're paying for and the piece of paper, such that it is, is just the evidence you succeeded in that.