You can learn a huge amount by reading a novel, examining an artwork, or watching a movie. You can usually learn a lot more by doing one of those things than you can by reading a school textbook that spoon-feeds you information.
But every day, I see people choose to read a textbook they’ve already read a dozen times over a new novel, because they can see an immediate reward for reading that book. Namely, that reward is better grades.
But getting better grades doesn’t mean you’ve learned more. Getting a better grade on a topic usually shows that you’ve trained your brain to regurgitate information on a given topic so well that your brain isn’t even conscious of it anymore. It wasn’t learning beyond the point that you understood the concepts – from there, it was simple memorisation.