Fresh off his shellacking of former New York governor #AndrewCuomo in the Democratic primary for mayor, New York state assembly member #ZohranMamdani is the hottest guest on the press circuit. When asked in an interview if he thought billionaires have the right to exist, he chuckled. “I don’t think that we should have billionaires,” he said, “because, frankly, it is so much money in a moment of such inequality.” The United States is a fiercely capitalist society based on the meritocratic idea that everyone has the opportunity to build their own futures—and fortunes. Billionaires typically make their money by starting companies that are engines of innovation, and which employ millions of their fellow citizens. Think Amazon. Nike. Wal-Mart. Microsoft. Google. If the U.S. were to enact a hyper-aggressive wealth and asset tax—the only way to truly attack fortunes of this size; most #billionaires have little in the way of ordinary income—it might push many billionaires to leave the country...