Back in the early aughts, back before Kevin Ryan was heralded as a grandfather of New York tech, he had been quietly building DoubleClick into a 1,500-person company. And then, with a snap, he sold it for $1.1 billion in 2005.

"I didn't miss it at all," he tells Inc. "There was nothing wrong with it; I just didn't want to spend any more time on ad tech."

It's a very different story for him a decade later, upon the sale of one of his more recent major entrepreneurial endeavors, Business Insider.

"I am going to miss it. I just love media and tech, and the BI property is great," he said over the phone Tuesday morning. "I feel like the way I felt when my first son went off to college. You're happy because he's happy and it's a good outcome. But I'll miss it."

The acquisition of Business Insider, which Ryan started in 2007 along with Henry Blodget and Dwight Merriman as Silicon Alley Insider, by German media giant Axel Springer was announced September 29. The price works out to about $450 million--10 times the $45 million in revenue Ryan says Business Insider expects to bring in this year.

Axel Springer and Business Insider have been in a courtship since last year; by January, the Berlin-based newspaper publisher, which has been making significant investments in its online presence, bought a minority stake in Business Insider and integrated itself into the company's board.

After getting to know the company better, Ryan says Springer execs called him in July and said, "listen, we'd like to make an offer." His response? "Look, anything is possible, but we are not thinking about selling," he says.

Ryan and Blodget had been growing the company reliably over recent years, and scaling journalistic output across its small network of popular business websites. To increase traffic, in 2015 the company hired 75 editorial staffers--increasing the total to 175. As revenue climbed, Ryan says the $100 million mark seemed within reach--so he and Blodget began to have conversations about going public through an IPO. They expected to do so in about two years, he said.

Soon, though, Springer came back with a better offer. Ryan worked to finalize it by the end of August.

"I never think about selling, when I'm running a business," Ryan says. "But--it's a business. If someone offers a good price you have to entertain it. And all the better, when you have to know it's a good home."

Blodget, for whom Business Insider is a sweet comeback from his own personal bust during the first dot-com boom, in July told New York magazine: "I think we're in a golden age of journalism," he says. "Digital advertising is growing fast, our revenue is growing fast, and I don't see anything that is going to stop that shift."

Ryan has a personal policy of not serving on the boards of other peoples' companies; probably wise considering he has six--now five--of his own to run. So he's stepping away from Business Insider altogether. He says founders who believe in their idea might take a page from his playbook in terms of persistence in establishing a vision for building a company that doesn't yet exist.

"We had so much trouble raising money even five years ago; there were no successful stand-alone media companies out there, and so many venture capitalists turned us down for that reason," Ryan says. "Being ahead of the curve is not a comfortable place, but that's where you have to be to succeed."

Now, however, it feels pretty good--especially because he continues to get emails from nay-saying investors years later saying, "you were right."