The U.S. market has never been more focused on one single bet—but AI’s payoff will likely take decades

Americans have placed an unprecedented bet on the transformative power of artificial intelligence.

The past 50 years of economic history suggests it won’t pay off, at least not on a timetable the market expects.

Not since the Gilded Age—when, in 1885, railroad stocks accounted for more than 80% of active trading on the New York Stock Exchange—has the U.S. economy wagered so much on a single theme.

When that bubble burst in the Panic of 1893, a third of railroads went bust, more than 500 banks failed, and the economy plunged into a four-year depression.

Today’s frantic AI buildout may be on a similar trajectory.

AI-related capital spending has surged to about 2% of U.S.

GDP , from near zero five years ago.

But this time, the AI wager is concentrated in far fewer companies than the railway mania ever was.

In January, the Federal Reserve Bank of St.

Louis reported that investments in information processing equipment, software, research and development, and data centers—four investment categories economists consider the closest proxies for AI investment—accounted for 39% of U.S. economic growth in the first three quarters of 2025, higher than the 28% those activities contributed in 2000, the peak of the dot-com boom.

Pantheon Macroeconomics calculates that without AI spending, U.S. corporate investment in equipment was negative last year.

Consumption, too, is heavily dependent on AI.

The top 20% of income earners now account for approximately 60% of all U.S. consumer spending , according to Moody’s Analytics.

The source of their wealth? The AI stock rally.