E-book piracy is thriving very well, considering what can be found with zero effort on the darknet
Don't confuse leechers with readers. Actually the active eBookz scene is rather small. The people scanning and proof-reading and formatting usually know each other. Some of them even would like the illegal scene to be closed to leechers, which are the ones who cause the problems by distributing without thinking.
And as much as I believe that most of the music leechers download is actually heard by them as most movies may be watched, I think very little of the literature is actually read. If it would be, these people simply wouldn't find the time to download all this material.
Reading still is a time-consuming hobby. You either download a lot or read a lot.