“My name is Khalid,” he tells me, and I want to believe him. After all, he has traveled the world as royalty—the son of the king of Saudi Arabia, no less. Leading international investors know him as His Royal Highness Khalid bin al-Saud. He moved in an entourage of Rolls-Royces and Ferraris, his every whim tended to by uniformed housekeepers and armed bodyguards. A suave British-born C.E.O. handled his business affairs, and a well-connected international banker marketed his investment deals to a select few, leaving him to live a life of astonishing excess.