I have three reasons for saying that, even as an adult with only a year and a bit of college left, I absolutely love YA novels.
1. The market for them is just bonkers. If I get a job in a publishing house as I would like to, that'd be the place to work. So I read them for the knowledge of the genre, in part.
2. The tropes are so obvious that I can read a longer YA novel in like a day. It doesn't make me work hard and it's almost a game to see how many of the YA tropes they use.
3. I love the creativity of the novels. Harry Potter, after all, is classified as a YA. The first book is more middle grade, but the writing level increases as Harry grows up. Others use myth, legends, history, or create entirely new worlds like the HP one. I can't dislike anyone who has creativity. Nonfiction bores the hell out of me because it's somebody writing about the amazing things somebody else did. I don't want to read something written by someone who has to talk about other people and what they actually did. If someone can create a new, imagined scenario and story, I don't care if it has every YA trope imaginable. I'd rather read that than nonfiction.