There was still some demand for the printed books, and apparently it was enough to generate some profit. They really are beautiful-looking books. You couldn't decorate your study with Encarta.
On a related note, according to Wikipedia (!): "Microsoft had originally approached Encyclopædia Britannica, the gold standard of encyclopedias for over a century, in the 1980s, but it declined, believing its print media sales would be hurt; however, the Benton Foundation was forced to sell Encyclopædia Britannica, Inc. at below book value in 1996 when the print sales could no longer compete with Encarta..."
8000 sold in 2010 at $1395 is more than $11 million in revenue. Even if the cost is high, presumably they still made a profit on it until quite recently too since they kept printing them.
Seems like this should have taken place ten years ago or more.