A step-by-step scenario of how an AI crash could unfold — bad news for anyone with retirement money in an index fund, and a warning about how much of the market now rests on one idea.

• Nvidia is owed roughly $30 billion for chips already shipped, and two unnamed customers make up 39% of its sales.
• AI data center firms like CoreWeave borrow heavily to buy chips, then use those same chips as collateral for more loans.
• Used chip prices have been falling, so the collateral behind those loans may be worth a fraction of what lenders assumed.
• The top ten stocks are now 40% of the S&P 500 — more concentrated than during the dot-com bubble — so a stumble in AI hits everyone's 401(k).
• Layoffs would spread fast: AI-sector job cuts already passed 120,000 this year, and the pain reaches coffee shops, pension funds, and workers near retirement.

Outlook: The technology is real and Nvidia would survive, but if AI revenue does not catch up to the debt that built it, the correction lands hardest on people who never made the bet.