Donating the book away technically forfeits your moral right to the “acquired” copy. Whoever benefits from the donation may otherwise have purchased a separate copy of the book.
Or should I just burn the book so I don't taint a potential book buyer? :D
In the extreme, someone could buy one DVD, rip it, and pass it on (for money or for free, it doesn’t matter) to a chain of hundreds of people who do the same and now all get to keep the movie digitally forever, while the copyright holder only sold the single initial copy.
My point is not to admonish anyone, just to point out how passing on the physical copy while keeping an uncompensated digital copy is inconsistent with the goal of compensating creators proportionally.