Earlier quoted context omitted.
It was purchased a single time, just like the original e-book that you pirate.
Every person in the world doesnt use a single library with a single copy. Every local library purchases one or more. How many did Zlib purchase? How many Zlibs are there?
Do you see it as... 1. Criminal 2. Immoral 3. Having downsides
I think we agree it's not criminal (as scale doesn't apply to a binary criminality judgement stealing a penny is as criminal as stealing a pound though punishment will vary).
Are you suggesting it's immoral? Because I can't see where you make such an argument.
Or are you saying well it has downsides as authors may earn less? It's likely book purchases are affected by libraries. I don't think the effect is as profound as people think.
Without that context it's quite hard to discuss this topic.