Not a waste at all! You learn all kinds of human behavior, language, and critical thinking from fantasy novels.

BUT if you want to read nonfiction, there are genres within that too. Even within self help, do you want to learn about psychology, health, business, interpersonal skills? Or maybe you’d be interested in memoirs, narrative nonfiction, history?

My best suggestion is go to a library or bookstore if you can and tell them what you like and they will give you ideas. Even if you don’t have that access, try highly rated books from lots of different genres until you find something you like. Also, don’t do it because you think you should, do it because you want to. So if that means you enjoy fantasy then go for it, but if you want to learn things go for that too. Just don’t read because you think it looks good for you to be carrying around “Rich Dad, Poor Dad” or something like that.