There are ~130 million US households, so if each copy were bought by a unique household and all 3 million copies were sold in the US, that would mean ~97.5% of US households don't have a copy. Maybe there's some huge multiplier on borrowing from libraries? Personally I've never heard of it, but it seems like it's pretty far outside of my bubble of interests.
Then a hundred Instagram and TikTok influencers make videos about the book.
Reading is at an all time low in the US, the majority of people who have heard of this book probably haven't read a single sentence of it. It's mostly coming from social media content about the book.
