Big investors are quietly selling tech stocks while ordinary retirement savers keep buying, which is bad news for anyone whose 401(k) tracks the S&P 500.

• Buffett's Berkshire is sitting on a record cash pile after selling most of its Apple stake, and Druckenmiller and Tepper have dumped much of their AI holdings.
• The seven biggest tech companies are spending almost every dollar they earn on AI data centers and chips, and now have to borrow to keep going.
• Much of the AI boom is circular: companies invest in each other's startups, and that money comes straight back as sales, making growth look bigger than it is.
• Those seven stocks are now over a third of the S&P 500, so an index fund is really a bet on a handful of companies.
• Pension funds are stuck buying them anyway, because their rules force them to track the index.

Outlook: If AI spending slows or antitrust cases bite, the drop could hit household savings hard and drag the wider economy down with it.