In the 1920s publishers offered low cost books to increase demand. Books were cheap enough that people would buy their own copies rather than wait for a friend to loan them around. When the depression started book sales dropped and publishers raised prices in an effort to keep their profits up. They also started a campaign to keep people from lending their books to others and tried to popularize the term "book sneak" for a person who would loan their books to others or for a person who would borrow rather than buy a book.
What the publishers want is for everyone to buy their own copy of the book and not borrow (even from a library) a copy of the book. Depending upon the study the publishers estimate that without the passing on of books sales would be 2 to 5 times what they currently are. DRM restricts this ability to pass on the books. Therefore the correct response from publishers should be to encourage people to switch from paper based books to eBooks by lowering the prices on eBooks to less than one-half of the pBook price.
For example, if I think a certain book is great and tell Bob (to pick a name) and he wants to read it I could just loan him my copy of the pBook. However since we both have Readers he cannot read my copy and must buy and download his own copy.
The ultimate in DRM books (IMHO) was William Gibson's 1992 "Agrippa (A Book of the Dead)". The package was designed to degenerate upon exposure to air and visible light and the 3.5" disk included with the text allowed you to view each page once and then it deleted the text so you could not go back and reread any part of the book. Thankfully the practice did not catch on.