Grad School in most STEM fields will look equally gibberish to you, so your question is almost like asking "Why do people do research?". The answer is to learn

Grad School in most STEM fields will look equally gibberish to you, so your question is almost like asking "Why do people do research?". The answer is to learn things that we didn't know before. In most STEM fields it's about how the world works, in math you discover eternal truths, which is pretty cool too.