One thing to keep in mind is that what gets sold and what gets copied are sometimes different works. A group of works that are not being bought can be copied, so you may see sales revenues go up for this group of creators, but it's another group of creators who get reproduced and not paid for.
The example that we heard here over and over is university libraries spending hundreds of millions, more than ever, on science and technical medical journals, and not paying the reuse rights for the copying of chapters, short stories, and plays that they upload on their learning management systems and share with their students.
There are two different groups of rights holders. One is primary sale, and the other is secondary revenues; one they pay for and one they don't pay for. The impact is not felt the same way. The fact that they pay for one does not give them a free pass to copying the other group of books.