Put another way, there's no difference in profit between:
10,000 book sales and zero pirated copies.
10,000 book sales and 10 million pirated copies.
The only thing left to argue about is what percentage of those pirated copies would have turned into book sales if the free versions had not been available.
10,000 book sales and zero pirated copies.
10,000 book sales and 10 million pirated copies.
The only thing left to argue about is what percentage of those pirated copies would have turned into book sales if the free versions had not been available.