Books

Hell no.

Fiction is just as, if not more, valuable as non fiction. Stimulation of the mind needs more than just facts. Non fiction is something you can pick up way easier via a documentary than by book, assuming similar degrees of adherence to fact. You can compact a biography into a few hours of watching that might take an entire day of reading, and get just as much information out of it.

Compacting fiction in the same way isn't always possible. Even fairly short books of fiction often suffer by being as short as a movie.

And that's ignoring any value judgement of the fiction. But it's true that not all fiction is equal in its ability to stimulate thought. I would argue that escapist, light fiction is just as valuable as something like Shakespeare or Hemingway, even though something like Beverly Cleary's Ramona books might not cause the reader to explore via thought in the same way or degree.

But if you want to place value judgements on fiction, there are definitely works of fiction that are much more useful in terms of stimulating thought and feeling than some random time-life grade history of the civil war. Hell, I'd argue that any piece of fiction is more valuable than badly written history or science. Badly executed non fiction serves to reduce accurate knowledge. Bad fiction just wastes the reader's time, it doesn't mislead them.