Less than one-fifth of the U.S. economy is expanding, yet this small segment is growing at such a blistering pace—driven by AI-related spending—that it continues to hold up the rest of the economy. We are living through unprecedented times, with no true historical corollary to today’s economic backdrop. Every cycle feels unique and unparalleled in the moment. What never changes, however, are human emotions and the way the herd responds to periods of greed and exuberance.