Books have been available for free for years -- at the public library. One the occasions when I do buy one instead of checking it out from the library, I pass it on to family and friends when I have finished reading it.
Both you and the library bought your copies. Anyone wanting to read your copy of the book has to wait until you finish with it. Anyone who wants his own copy of the book has to buy it.
Suppose, however, that you or the library could simply print an unlimited number of copies of the book and give them away. Would the author see a dime of royalties from those additional copies?
I just noticed your tagline (Free Books!). I do hope you are aware that there is no such thing as a free book, if by "free" you mean "without cost." Any book worth reading costs someone to produce. The question is, who will pay the cost?