The headline isn't accurate. "No One Buys Most Books" maybe, but the article talks about books that sell more than 300,000 copies in a year. 90% of books sell fewer than 2000 copies in a year, but 2000 is actually a decent number, especially considering it will be a lot more than 2000 over the lifetime of the book.
There's more to this as well. You have to factor in that a lot of people write books because they want to say they wrote a book, and others do it because it supports their professional brand, so there was never an intention or expectation of selling a thousand copies.
The article doesn't say these books sell 2000 copies a year; it says they sell 2000 copies, period. Generously assume a $30 new release hardcover cost ("The City Is Up For Grabs", the most recent book I bought, cost $25) and a 20% gross margin for the publisher, and you're talking $35k total to split between the publisher and the author.
It does talk about celebrity books selling some low number of copies within the year of publication. Presumably those books do keep selling at some level for some long tail of the book being in print. But unless books are utterly unlike all other media, 80-90% of the proceeds from selling the book will come during the new release window.
Also, the author conflates fiction with non-fiction. No kidding, if you include science books , guides, how-to books, etc. most books do not sell many copies, but they are not expected or intended to. It's not like the market for calculus books is that big. Fiction books by major publishing houses for a general audience still sell a lot.
Fiction only sells a lot if you hit the best seller lists. Most books do not, and it has been this way since at least 2000. For most fiction authors, you would make more money at a minimum wage job. You know, all the ones you haven't heard off because they didn't hit the best seller lists.
There's more to this as well. You have to factor in that a lot of people write books because they want to say they wrote a book, and others do it because it supports their professional brand, so there was never an intention or expectation of selling a thousand copies.