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.

Ever since he was a boy, he had been pitted against his royal brothers in an expensive game—to see who could “outdo the other one” in spending, he liked to say. Khalid was surely winning. He was in negotiations to purchase 30 percent of the famed Fontainebleau hotel in Miami Beach for $440 million, and he was selling early access to what promised to be the biggest I.P.O. in history: the initial public offering of Aramco, the Saudi oil giant. Until last June, when the Saudi government shelved the plan, the I.P.O. was expected to be worth more than $2 trillion.

Khalid could regularly be overheard talking on his phone with the likes of Bill Gates and Presidents Barack Obama and Bill Clinton. “I’m sick and tired of Trump calling me and inviting me to the White House!” he often complained. He kept in touch with his father, the Saudi king, on FaceTime, and, if you were lucky, he would let you listen in. But the prince’s favorite companion was Foxy, his beloved Chihuahua, whom he draped in diamonds and designer dog clothes and toted around in a $2,690 Louis Vuitton dog carrier. He stuffed other Louis Vuitton bags with stacks of $100 bills, tossing the money from his jewel-encrusted fingers, one sporting a nine-carat diamond, to those who tended to his needs—flashes of benevolence from an academic genius whose LinkedIn page lists his law studies at Harvard, his master’s in business administration from the University of Southern California, and his top marks at Institut Le Rosey, the elite Swiss boarding school attended by Rockefellers and Rothschilds.

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