This is not correct. In economic terms if person A values a book at a price below the selling price and pirates it, the seller has not lost income compared to the counterfactual world where piracy was impossible.
That's not true, person A could still send the author money by other means, but really in that situation a trade should not take place because it is against the seller's consent.
I was assuming that the other means have transaction costs higher than the value to person A because this is the case in the real world (how many authors even have a Patreon?).