One week ago, Elon Musk was standing in the Oval Office, receiving a large gold key from President Donald Trump. It was Mr. Musk's last day as a "special government employee," and he was being lauded for his work aimed at slashing "waste, fraud, and abuse" as head of the newly formed Department of Government Efficiency, or DOGE. Six days later, the two men -- the richest person in the world and the leader of the free world--" were at each other's throats on social media, hurling insults and threats in perhaps the most extraordinary political breakup in modern American history.