While the rest of the U.S. economy reeled from devastating losses in 2008-9, the tech sector looked on sympathetically while wondering to itself, "Are things really that bad?"

The big picture: That's partly because the tech industry was well insulated from the financial meltdown's real-estate-focused epicenter. And Silicon Valley had already experienced its own financial bust at the start of the decade, leaving the industry with more solid growth and less hot air.

For tech, the 2001-2 recession — considered mild in most of the nation — was epic, scarring.

• After the dotcom bubble popped, the tech-heavy NASDAQ index lost 3/4 of its value between March 2000 and Dec. 2002.
• A generation of software developers and designers got to know what it's like to be laid off. San Francisco's South of Market neighborhood — today, a hive of startups and chic luncheries — became a ghost town.
• If the NASDAQ today experienced a drop like it did in 2000-2002 and the index lost 3/4 of its value, it would fall to 2000, squashing today's cushy portfolios, beheading unicorns and destroying trillion-dollar valuations.

The industry experienced only limited recovery during the mid-2000s, took a brief dive again during the 2008 crisis, and then jumped on a bull for a decade, rising from its spring 2009 low near 1300 to around 8000 today (that's a 600% return).

Modern tech has always been a cyclical industry, but its boom-bust pendulum has been stuck on the side of growth for a full decade now:

• Cash has flooded in as investors around the world looked for higher returns during a long era of near-zero interest rates set by central banks trying to stoke a broader recovery.
• Technology investments from previous eras — in everything from fiber backbones to wireless broadband to more versatile software development tools — delivered big payoffs.
• Innovations in machine learning and AI, device miniaturization, cryptocurrency, and autonomous vehicles held out one promise after another of uninterrupted growth.

The bottom line: Tech is hardly immune from future downturns, and any number of disasters — from a full-on trade war with China to a massive earthquake along the San Andreas — could trigger a race to the exits.

• A single big bust is less likely than a series of smaller pops, as enthusiastic investors and funds overplay their hands on one tech fad after another. For instance, a lot of experts think there's a bubble in scooters right now.