> according to data from the Authors Guild

Despite the narrative that copyright holders in every industry like to push, a pirated copy is not equal to a lost sale. Their actual losses are likely a small fraction of that number.

Is the thinking that the person who pirated it was never going to buy it anyways?

They may or may not have bought it, but the calculations of "lost sales" assume that 100% of them would have bought it at full price, which is absurd. I'd wager it is closer to 10%.

In my lifetime I've easily bought 100x more books used than new, which (from their perspective) is economically indistinguishable from piracy. Any of those "lost sales" estimates strike me as entirely bogus.