It did not help that Silicon Valley and San Francisco started to feel—and very much still feel—detached from reality. Tech bros were disrupting eating disorders, taking hallucinogens to improve their productivity, and paying to freeze themselves so they could live forever, all while shelling out $2,000 a square foot for housing and taking private jets to go on vacation. The writers of HBO’s Silicon Valley found at least one real-life meeting with a denizen of Silicon Valley too absurd to be used as grist for the show. With the rest of the economy limping along, the Bay Area felt like Gomorrah before the fall. But the party just kept going.

It kept going in part because vastly more money was sloshing around than people initially realized. Source one for that cash: foreign investors, particularly ones based in China, Saudi Arabia, and Japan. Firms such as SoftBank have funneled astonishing sums into the pockets of start-up founders and early investors, helping prop up tech valuations and allowing early-stage investors to cash out. (It seems worth noting that tensions between Beijing and Washington have led to a collapse in Chinese investment in tech in recent months.)

Source two: the giants that form the highly profitable headwater of the broader tech ecosystem, such as Amazon, Google, and Facebook. These companies have flushed hundreds of billions down to smaller, younger firms and their investors in the form of acquisitions and acquihires. Facebook spent $20 billion on WhatsApp and Instagram; Microsoft spent $26 billion on LinkedIn and $7.5 billion on GitHub. Deals such as these were possible only because those acquiring companies were themselves so very profitable. More broadly, the tech dura-bubble has coincided with a continued boom in corporate profits that has lifted valuations and increased the sums spent on mergers and acquisitions throughout the whole economy.

All that capital from institutional investors, sovereign wealth funds, and the like has enabled start-ups to remain private for far longer than they previously did, raising bigger and bigger rounds. (Hence the rise of the “unicorn,” a term coined by the investor Aileen Lee to describe start-ups worth more than $1 billion, of which there are now 376.) Such financial resources “never existed at scale before” in Silicon Valley, says Steve Blank, a founder and investor. “Investors said this: ‘If we could pull back our start-ups from the public market and let them appreciate longer privately, we, the investors, could take that appreciation rather than give it to the public market.’ That’s it.”

Those private investors have, in turn, eaten the losses when start-ups have failed, as many of them have. There are fewer IPOs now than there were during the last, true tech bubble, and many venture-backed companies that have gone public have done so far later than they did the last time around. If there was a bubble and it were to burst, kitchen-table investors might scarcely notice, unlike in the late 1990s.