I have never borrowed a book from a library and then later bought the same book. On the other hand, some of the pirated ebooks in my collection have turned out

I have never borrowed a book from a library and then later bought the same book. On the other hand, some of the pirated ebooks in my collection have turned out to be valuable enough to sell me on the convenience of owning a physical copy. Your anecdote vs. my anecdote. I think that neither of us has a very strong case that piracy and/or libraries help authors sell more books.