Back in early 2007, when he was just 22 years old and running a company of about 20 million registered users, Facebook CEO Mark Zuckerberg told a crowd at the Y Combinator Startup School event at Stanford that “young people are just smarter.”

“Why are most chess masters under 30? I don’t know,” he said. “Young people just have simpler lives. We may not own a car. We may not have family…I only own a mattress…Simplicity in life allows you to focus on what’s important.”

“I want to stress the importance of being young and technical. If you want to found a successful company, you should only hire young people with technical expertise,” he said.

Now, Zuckerberg has a wife and more than a few mattresses. He also turns 30 today.

Mark Zuckerberg has just exited his self-proclaimed window for youthful intelligence. “Move fast and break things” has been replaced with “Move fast with stable infrastructure.” Holy hell–Mark Zuckerberg is an old man now.

Of course, Mark Zuckerberg is not old. He’s young and incredibly intelligent. He runs a company with over a billion users and basically has a billion dollars for every year he’s been alive. It’s just funny when your words come back around and give you a little nip on the ass.

Especially considering the culture of ageism that exists in Silicon Valley, one that’s forcing people to do some pretty drastic things to get funded noticed.

In a recent conversation with Farhad Manjoo for the New York Times, Zuckerberg deflects and refocuses when asked about turning 30.

“…[M]ost people who use Facebook have not been my age through the majority of my time here. But understanding who you serve is always a very important problem, and it only gets harder the more people that you serve. We try to pay a lot of attention to this by a combination of very rigorous quantitative and qualitative feedback. But if you’re serving 1.2 billion people, it’s very hard.

And I think the age thing is probably not the biggest one I worry about…”

Zuckerberg worries about his venture internet.org, about the long-term viability of Facebook and creating “stable infrastructure.” He probably worries about a lot of things–but I’m guessing age isn’t one of them. I wonder what 22-year-old Zuck would think of 30-year-old Zuck?

Image via Mark Zuckerberg, Facebook