If you think studying literature is to teach you literature, you're sorely mistaken. Similar to if you think you study mathematics to learn mathematics.

You are taught literature so you can better communicate with other people. What is the author's intention with this passage? What are they trying to say? What might their motivations be? Now apply this to a letter from a potential business partner or a politician's tweet and you might begin to see how what you were taught becomes relevant.

Why are you taught grammar? Who cares whether you use the Oxford comma or not? Who has the need to know what mood, theme, and figurative language are? Apply this in the context of trying to write a professional email to your boss or trying to tell a story to engage other people, and maybe you'll start to see that it wasn't worthless.

Why do we need to know the way to prove that the angles of a triangle add up to 180? Who needs to know the Quadratic formula and how to apply it? It's so you know how to think rationally and apply logic rigourously, so you don't fall into familiar logical traps that we see on the evening news and the Internet every day.

Why do you need to know how cells reproduce? Why do we need to know how the pH scale works? It's so when people on Facebook claim that vaccines erase your DNA or that alkaline water prevents cancer, you'll know better.