According to a new book, Madonna got played when she was selling her stake in Maverick in 2003—she wanted $60 million, then $200 million, was sued when she balked at $15 million...but wound up taking $17 million in the end. I wish I were this "foolish!"

Also of note—when her bosses wanted to placate her after the fact, they gave her diamonds, over which she reportedly cooed. But for me, the ultimate lesson is that Madonna eventually left Warner Bros. anyway.