Textbooks aside, the people that can live as full time writers are either good enough that people want physical copies or they are already propped up by a publisher who keeps them around for diversity and no one is buying their stuff anyway.
The difference between a book whose target audience is students vs the general public is often a factor of 10 or more.
Back when printing required physically making plates and limited print runs meant recouping high fixed costs is over. The old justifications no longer apply, but the market hasn't corrected because it is controlled by a cartel.
Textbooks aside, the people that can live as full time writers are either good enough that people want physical copies or they are already propped up by a publisher who keeps them around for diversity and no one is buying their stuff anyway.
Most regular books are much more reasonably priced than most textbooks, as well.
The difference between a book whose target audience is students vs the general public is often a factor of 10 or more.
Back when printing required physically making plates and limited print runs meant recouping high fixed costs is over. The old justifications no longer apply, but the market hasn't corrected because it is controlled by a cartel.