“Inventing the printing press was not the same thing as inventing the publishing business. Technologically, craftsmen were ready to follow Gutenberg’s example, opening presses across Europe. But they could only guess at what to print, and the public saw no particular need to buy books. The books they knew, manuscript texts, were valuable items and were copied to order. The habit of spending money to read something a printer had decided to publish was an alien one.”
— At The Boston Globe, an interview with Andrew Pettegree on how it took people a very long time to figure out the business of publishing after the invention of the printing press.
He also tells the story of how Gutenberg himself was thrown out of the printing press business by his partner because he kept losing money printing Bibles.