Paul McCartney has been known for some time as the richest musician in the world, holding a fortune just over $1 billion. As a member of one of the biggest musical groups in history, it isn't hard to believe that is possible. With Facebook starting public trading of stock in the company, a savvy investment has a new rock star owning that title.

Bono of U2 made a $90 million Facebook investment in 2009, giving him ownership of 2.3 percent of the company. That investment, at the end of today, will end up offering a payday of an estimated $1.5 billion. Must be tough being a high-profile rock star, right?