You're twisting the argument. Pirates aren't copying content in a sealed room, they are distributing it to people for free. If you kept making copies of Harry Potter and gave it to anyone for free, it's not delusional to argue that JK Rowling would be far poorer than she is now. Harry Potter is an exceptionally popular product so the reduced revenue may still be enough for JK Rowling, but less popular and more niche content may not work out well enough for their content creators.