He was once called “Dr. Doom and Gloom” on Wall Street. Not everything has changed for Kent Smetters, who runs the Penn Wharton Budget Model. His economic predictions remain gloomy, but imminent doom isn’t around the corner.

In his view, doom will land on America’s doorstep between 2045 and 2050, the breaking point for the U.S. economy. That’s the moment when, as Smetters sees it, the cost of interest payments on the national debt would become so large for the federal government that even a broad-based tax increase wouldn’t cut it anymore.

At that point, Smetters says, the U.S. government would enter either an explicit or implicit default, both with calamitous consequences. An explicit default renders the U.S. a global deadbeat. An implicit default theoretically occurs through debt monetization — which jacks up inflation — or by trimming Social Security and Medicare payments.

“This is when panic starts happening. This is the loss of faith in government,” Smetters told me. “That's what's doomed other societies as well. Before us, you can go all the way back to Rome, to France, Spain, the U.K., and Germany. Almost every empire has been taken down by debt.”

Smetters is part of a familiar group of fiscal hawks cycling in and out of Washington, which has all but surrendered to a national debt that swells in size with every passing day. The gross U.S. federal debt surpassed $38 trillion in October, per data from the Treasury Department. Put another way, total U.S. debt has grown by $66,225 each second so far in 2025, according to the Joint Economic Committee in Congress.

Those are staggering figures. But the growing U.S. debt isn’t likely to be tamed anytime soon. President Donald Trump and a GOP-led Congress brushed aside concerns about fiscal discipline when they muscled through the so-called “Big Beautiful Bill” with a $3.4 trillion price tag this summer.