But now Mr. Steltenpohl, a gentle and avuncular 62, is once again near the center of beverage industry buzz as the head of Califia Farms, a nut milk business that is fast expanding into bottled coffees and other drinks. This time, he is taking advantage of a new trend sweeping the industry, as young beverage companies — empowered by changes in distribution and consumer tastes — are rising and competing successfully with titans like Coca-Cola and PepsiCo.

Today it’s possible for a company to develop a drink and cut a deal with an assembly line for hire to produce it, and negotiate another deal for someone to distribute it. Just a decade ago, it required far more capital and, eventually, a sprawling operation.

Only a few years after its founding, in 2012, Califia is on track to ring up $100 million in sales and is adding products at a fast clip. The company is considered one of the hottest young brands in the beverage world, leading to whispers about whether one of the big competitors will soon swoop in with a buyout offer that Mr. Steltenpohl and his partners can’t refuse.

Not this time, he insists. “I’ve had to sell out once,” Mr. Steltenpohl said. “That was enough.”

That’s easier to say than to do. A little more than a month ago, Ben Weiss, the founder of the flavored water company Bai, also brushed back talk of a buyout. “It’s called Bai, not Sell,” he said in an interview at the time.

His argument was not unique these days. He had already teamed up to a degree with one competitor. The company’s drinks, which it called “enhanced waters,” got some distribution from Dr Pepper. And Bai was outselling a competitor in retail stores: Over the previous 12 weeks, Bai had outsold Vitaminwater, a Coke brand, for the first time, Mr. Weiss said.