It's more complicated than that; in the 19th century when libraries (at the time mostly subscription ones akin to a Victorian Netflix) were the primary purchase

It's more complicated than that; in the 19th century when libraries (at the time mostly subscription ones akin to a Victorian Netflix) were the primary purchasers of books rather than individuals, novels were extremely expensive -- the typical novel at the time was a rambling 1000+ page affair taking up three volumes https://en.wikipedia.org/wiki/Three-volume_novel https://en.wikipedia.org/wiki/Three-volume_novel) and cost over 30 shillings. That's like £150 or $200 today! It was the decline of the subscription library that forced publishers to sell books to individuals at a more reasonable price and eventually invent the idea of the paperback