Printing a book on paper and distributing physical books isn’t the majority of the cost of a book. Should ebooks be cheaper? Yes should they cost a fraction of a paper book? No since most of the cost in publishing does not depend on the medium of distribution. Most of the cost is basically the salaries of the people they have to pay to get the book onto the market (the writer, editor, marketing, etc) it doesn’t matter if it’s digital or physical these costs stay the same. Publishers basically lose money with the majority of the books they publish and make most of their money with the few hits they release each year.