The battle of the billionaires continues. Late Sunday night, Jeff Bezos tweeted out an old Barron’s cover story that doubted the future success of Amazon, telling followers to not “let anybody tell you who you are.” “This was just one of the many stories telling us all the ways we were going to fail,” he wrote. “Today, Amazon is one of the world’s most successful companies and has revolutionized two entirely different industries.” Billionaire Elon Musk replied with a cheeky tweet—a silver medal emoji— reminding the Amazon founder he’s not the world’s richest person anymore. Musk secured that title in September, when he became just the third person with a fortune of more than $200 billion. “I’m sending a giant statue of the digit ‘2’ to Jeffrey B., along with a silver medal,” the Tesla founder told Forbes at the time.