Do you know how much money Jim Butcher actually saw from that? I don't... maybe it was a big windfall for him. But "Hollywood accounting" is pretty infamously creative about such things.

You know the movie Forrest Gump? Number one box office smash, cleaned the clocks of the competition at the Oscars, critically acclaimed, etc.? Apparently it lost the studio a ton of money. Yeah. So when it came time to pay the author of the book whose title they'd bought his share of the profits... oops, there are none! The film was a big money loser. He's lucky they didn't charge him.

Then they turned around and wanted to buy the rights to the second novel, and he told them that he good not, in good conscience, allow them to waste more money on a proven failure. Hee hee hee.