In terms of staying power, the current bull market has some advantages over past sprees, when a surging stock market fused financial speculation into the fabric of American life.

In the 1920s, Americans dived into the market to snap up shares of a range of companies churning out the technological marvels of the day, like automobiles and radios. In the 1980s, as the country recovered from a deep recession, Wall Street enjoyed a broad boom grounded in Reagan-era deregulation and economic growth.

In the 1990s, retail investors poured their money into high-flying, and in many cases profit-free, companies developing around the emerging technology known as the internet. And in the years before the financial crisis of 2008, the stock boom was coupled with the excesses of the housing market and Wall Street.

“You were in some sort of a dreamy state, and it couldn’t last,” Allen Sinai, chief economist at the consulting firm Decision Economics and a former chief economist at Lehman Brothers, said of the dot-com era. “The taxi drivers, the elevator operators, everybody was into the stock market and buying. It was euphoria.”

“Today the sentiment that’s out there is actually more to the opposite,” he added. “It’s cautious. It’s careful. ‘Recession is coming tomorrow. How long can this go on?’”

It’s a natural question to ask. Those euphoric periods ended in spectacular stock market crashes, in 1929, 1987 and the early 2000s and during the financial crisis.

But the same frothiness doesn’t exist now, suggesting there is little immediate risk that the market will do a 180.