"I'm not in a bubble! YOU'RE in a bubble!" Ethan Miller/Getty Images What links Walmart's $3 billion purchase of Jet.com, Unilever buying up Dollar Shave Club for $1 billion, and GM buying Cruise for $1 billion?

They're all examples of smaller startups being acquired by dominant incumbent rivals. And according to Dave McClure, a venture capitalist at the investment firm and startup accelerator 500 Startups, they're indicative of a bubble — but not where most people think.

Bubbles are among the tech sector's favourite topics of discussion: Is the industry in one? And what happens when it pops? With huge volumes of venture capital sloshing around, and the increasing proliferation of billion-dollar-plus startups, known as unicorns, plenty of people think there's a tech bubble.

And amid a decline in VC funding and valuation write-downs of some of Silicon Valley's darlings (including Snapchat), we may already be in a contraction, the argument goes.

But McClure takes the opposite approach. "Most unicorns and many tech IPOs are perhaps overvalued, but a few of them are actually UNDER-valued as well," he argues in a new blog post. The investor points to Facebook as an example of how tech company valuations can skyrocket postvaluation — and makes the case that if anyone is in a bubble, it's the traditional incumbent companies, ripe for disruption.

Of course, McClure works in the venture capital business, so it's no surprise that he's trying to talk down the idea that he might be contributing to an unsustainable bubble. He has his livelihood and the valuations of his investments to think about.

With that in mind, it's an interesting argument, not only for its own merits but also because of what it tells you about the vision of boundless meritocratic "disruption" that startup investors are trying to sell to the world.

Is that unicorn a dog in disguise? John Moore/Getty Images

McClure asserts: "The REAL bubble is in far-too-generous P/E multiples and valuations of global public companies, whose business models are being obliterated by startups and improved by orders of magnitude."

As a result, he argues, we should expect to see plenty more acquisitions like Walmart's purchase of Jet.com, as the incumbents wake up to the threat that smaller startups are posing and attempt to "hedge their own public valuations by buying the very same unicorns that keep them awake at night."

He goes on (emphasis ours):

"Of course, this might be risky, but it's no more risky than not doing anything and expecting to keep your CEO job intact and the stock price rising. Hedging your public company stock by buying potentially disruptive unicorns for only 5–10% of your market cap may be one of the simplest ways to defuse the startup threat and keep on trucking ... this is the Unicorn Hedge.

...

"No surprise, most of the now-public tech giants are investing in and buying OTHER tech startups and unicorns to stay on top of their game. Microsoft bought LinkedIn and Skype. Google bought YouTube and Android. Facebook bought WhatsApp and Instagram. In fact in the past five years ALL of the top 5 highest-value public companies are tech companies. So what do you think is more overvalued? The average unicorn or tech IPO? Or the average non-tech public company that hasn't innovated in over a decade?"

These allegedly non-innovative public companies, McClure argues, are ripe to come crashing down (emphasis ours):

"The REAL twist is Wall Street finance getting disrupted by Silicon Valley tech (and, by NYC and LA tech too). The REAL twist is the S&P 500 not realizing their avg P/E multiple should be ~5–10 instead of ~15–25. The REAL twist is big oil & gas and automotive companies not realizing their market caps aren't just overvalued, but that in 10–20 years THEY WILL GO TO ZERO as electric power and autonomous vehicles become the norm. The REAL twist is thousands of public companies hemorrhaging billions in losses and value over the next ten years, like gigantic, collapsing Manhattan skyscrapers in slow motion … except that it might not be that slow."

In short: It's the traditional billion-dollar companies that are overvalued — not the startups that are planning to eat their dinner.

It's certainly true that some big incumbent companies will be toppled by the next generation of entrepreneurs. But even the most ardent bubble-theory advocates wouldn't disagree with that. It's the extravagant spending in some corners of startup culture and the allure of meteoric growth and hyperbolic investor promises that are in question.

And as McClure points out, these incumbents are more aware of — and taking steps to counteract — the threat posed by startups than ever before.

At the same time, when multibillion-dollar startups can blow through hundreds of millions of investor dollars before imploding — or hire hundreds of employees and then close without ever launching a proper product — it gets harder and harder to believe that the tech sector isn't at least a little inflated.