When President Donald Trump began his tariff rollout, the business world predicted that his unprecedented attempt to reshape the economy would lead to a major recession, if Trump went through with it all. But the markets stabilized and, in recent months, have continued to surge. That has some people worried about an even bigger threat: that overinvestment in artificial intelligence is creating a bubble. Andrew Ross Sorkin, one of today’s preëminent financial journalists, is well versed in what’s happening; his début book, “Too Big to Fail,” was an account of the 2008 financial crash, and this year he released “1929: Inside the Greatest Crash in Wall Street History—and How It Shattered a Nation.” He tells David Remnick that the concern lies in the massive borrowing to build the infrastructure for a future A.I. economy, without the sufficient revenue, currently, to pay off the loans. “If I learned anything from covering 1929, [and] covering 2008, it is leverage,” Sorkin says, “people borrowing to make all of this happen. And right now we are beginning to see a remarkable period of borrowing to make the economics of A.I. work.” Sorkin is the co-anchor of “Squawk Box” on CNBC, and he also founded the New York Times’ business section, DealBook.