"Mark Twain said boxing is the only sport where a slave, if he's successful, can rub shoulders with royalty," says former heavyweight Mike Tyson, who once knocked out 19 opponents in a row. "Can you imagine that? Just by fighting another human being, he can meet a king, a prince, a queen, eat at the same table with them, be invited to the castle." Or in modern times, make $30 million in one fight, build your own castle, stock it with tigers, and still wake up every morning the pawn of powerful men who make money off your sweat. When...