Margin debt has climbed to a record $1.5 trillion, amplifying gains in rising markets but creating forced-selling risk when sentiment shifts. Records stacking simultaneously across ETF flows, leverage, AI spending, IPO valuations, and federal debt leave the market almost no cushion for disappointment. Even more striking, inflows are running more than twice the pace seen at this point in both 2021 and 2025. The surge reflects investors' confidence that AI investment, corporate earnings, and economic growth can continue supporting higher stock prices. The problem is that record optimism usually leaves less cash on the sidelines to cushion markets when sentiment changes.