Reading didn't decline as much as you imply here. Reading was "niche" even 20 years ago.
[1]: https://ideas.bkconnection.com/10-awful-truths-about-publish... It assumes book price trend = CPI, but I don't buy it. Recreational books are one of the few things that have become cheaper [2], likely due to e-books.
[2]: https://www.in2013dollars.com/Recreational-books/price-infla...
at least the omegaverse is not formulaic to the hilt
and also has actual smut