​Venture capitalist Saul Klein says big companies shouldn't jeer when Google buys Nest for $3.2 billion or Facebook buys WhatsApp for $22 billion. Of course, he's a salesman with a job to do.

DUBLIN, Ireland -- The established companies that snicker to see Facebook lay out $22 billion for the WhatsApp messaging app are the same ones most like to go extinct in today's fast-moving business world, venture capitalist Saul Klein said Tuesday.

Of course, at Index Ventures, Klein is a salesman who tries to get those established companies to buy his startups once he's helped fund and build them. But at the Web Summit here, he made the case that he's not just looking for a quick exit for his portfolio of companies.

"The average lifespan of big company has gone from 50 years to around 10," Klein said. "In the last 20 years, over 220 billion-dollar unicorns were born," he said, referring to startups that make it big.

Those who laugh now at big investments are likely the same people who laughed when Google bought YouTube for $1.65 billion a decade ago. That property is now worth something like 100 times that amount, Klein argued, and Google's acquisition or home-monitoring company Nest shows similar foresight.

Ever-increasing valuations for startups are the kind of thing that could signify a new tech bubble, along with mammoth initial public offerings, $250,000 salaries for engineers and a San Francisco that's not affordable for mere mortals. But so far, investors have been willing to continue injecting their money.

Klein thinks there's a reason it's so hot right now: The world's population is coming online, and fast.

"It takes less and less time to create an extraordinary amount of value," Klein said. In the time it took WhatsApp to reach 400 million users, earlier startup wunderkind Skype had reached only about 50 million.

Those who succeed are those who tap into the growth -- and much of that is happening in China, India, and other countries far from the traditional technology centers.

"There are more people online in Nigeria than the UK," Klein said. "All the growth is happening out there."