Money is pouring into cryptocurrencies at a furious clip. You can call it a bubble, or the Wild West. Some say it’s reminiscent of dot-com stocks in 1999, or “tulip mania” from 400 years ago.

There’s plenty of speculation, to be sure, and more risks than we can count.

But for entrepreneurs and tech investors, crypto and the underlying blockchain technology has a particularly attractive quality that’s unique in today’s tech landscape — it’s about the only high-growth area not occupied by the industry giants.

Think about all the buzzwords like cloud, robotics, internet of things, virtual reality and artificial intelligence. In each case, the names that come to mind are Apple, Alphabet, Amazon, Facebook and Microsoft.

Those five companies are worth a combined $3 trillion and have $530 billion in cash. They’re big, getting bigger and building the computing platforms of the future.

For Chris Dixon, a partner at venture firm Andreessen Horowitz, their relative absence from crypto and blockchain is a welcome sight.

“A big challenge in the start-up world is that we live in an era of very powerful incumbents,” Dixon said, in a recent interview with CNBC.

Dixon has led his firm’s investments in Coinbase, a site for buying, selling and storing cryptocurrencies, and Keybase, a cryptographically-protected chat service. Andreessen Horowitz has also backed Polychain Capital, a hedge fund that invests in digital currencies.

In the second quarter, equity investments in blockchain start-ups jumped 44 percent to $232 million, according to CB Insights. The bigger boom is in initial coin offerings (ICOs), which are unregulated sales of digital coins or tokens that crypto projects are using as a new form of currency. Over $1.2 billion was raised through ICOs in the first half of 2017, according to Autonomous Research.

Not to confuse quantity with quality. Most of this stuff will surely go to zero, and eventually the SEC will have plenty to say about it.

But for now, there’s a lot of wiggle room, as the tech leaders invest around the edges of blockchain while focusing their time and money elsewhere.

“I can’t imagine they view any of what’s happening right now as a competitive threat to their business,” said Barry Silbert, founder and CEO of Digital Currency Group (DCG), which invests in an array of blockchain companies, projects and currencies. “They’re not going to be a first mover. They’re going to watch innovation happen, they’re going to learn, sit on the sidelines and to the extent they see something that plugs in nicely to their business model, they’ll acquire.”

It’s important to differentiate between blockchain and crypto.

The blockchain is a distributed electronic ledger that allows all transactions such as payments, loans and contracts to be tracked in real time. Cryptocurrencies are an application of blockchain technology that take advantage of its decentralized nature to create alternative forms of money that aren’t tied to central banks. Hundreds of crypto projects have created their own currencies.

While the tech giants are practically non-existent in crypto, they’re at least paying attention to blockchain and putting a little money to work.

Microsoft has a product in its Azure cloud called blockchain as a service, which essentially hosts blockchain start-ups and workloads. Amazon Web Services was working on a similar offering with DCG as of a year ago, according to a Forbes story, though no official announcement has been made.

Most of Alphabet’s activity in the market is through its venture arm GV, which has backed start-ups including Blockchain (the company) and Ripple, a distributed payments network used by banks. Google’s AI unit DeepMind is using a blockchain-like ledger to track and protect medical data.

Apple and Facebook, meanwhile, have been near silent on the subject.

The most vocal of the big vendors has been IBM, which said last month that it’s building blockchain technology for seven of Europe’s largest banks to facilitate international trade for small and medium-size enterprises. CEO Ginni Rometty said at a conference in January that IBM is using blockchain internally to track financing and is also working with large retailers and shippers, implementing blockchain throughout global logistics systems.

It’s all early and there remain opportunities for upstarts to create new blockchain platforms.

Crypto projects are even less proven, as there haven’t been any breakout use cases other than bitcoin as a store of value, albeit a quite volatile one.

Investors see a promising market where Jeff Bezos and Mark Zuckerberg aren’t yet lurking. Josh Hannah, a partner at venture firm Matrix Partners, has been buying cryptocurrencies for his own accounts but isn’t yet betting his firm’s money on any projects or start-ups.

He’s waiting and watching.

“Most of this is much closer to the research end than we usually play,” said Hannah, who previously helped create betting site Betfair. “If crypto delivers on its promise, then it could be one of those platform disruptions, which would be great for entrepreneurs and VCs.”

That is, Hannah notes, “unless this one disrupts VCs.”