I found an interesting editorial from the Huffington Post:
Once upon a time, the only books that existed were books copied by hand by monks and scribes and sold to the very rich for the equivalent of $5000 or $6000 a book. Then along came the printing press, and all the monks and scribes had to find another way to earn their bread.
Once upon a time the only books that existed were books on paper made by printing presses and sold to the rich and not so rich and not rich at all for enough money to make publishing houses worth hundreds of millions of dollars, enough money to pay high salaries to publishing executives. Then along came the digital book, and many thousands of people in and around publishing had to find another way to earn their bread.