Google's (Nasdaq: GOOG) Eric Schmidt laments the one that got away.

Speaking at All Things Digital's D9 conference last night, the search giant's former CEO fessed up on missing the boat with Google.

"I clearly knew that I had to do something, and I failed to do it," Schmidt said after reflecting on memos he wrote concerning the company four years ago. "A CEO should take responsibility. I screwed up."

He shouldn't feel bad. He's definitely not alone in underestimating the eventual popularity of Facebook and its far-reaching implications.

These days we find folks logging into many community and deal websites by simply using their Facebook information. Social gaming, chatting, and email are taking place within Facebook's walls, where its roughly 600 million members are largely happy captives.

If Google had beaten Facebook at its own game -- or simply acquired Mark Zuckerberg's sticky creation -- it would be an even bigger and more relevant dot-com juggernaut than it already is today.

It's hard to blame Google, though.

Where was Facebook four years ago?

 

Users

8/26/08

100 million

4/8/09

200 million

9/15/09

300 million

2/4/10

400 million

7/21/10

500 million

Source: blog.facebook.com.

Google had -- and has -- Orkut. News Corp. (NYSE: NWS) was the envy of the niche with MySpace. AOL (NYSE: AOL) wound up paying $850 million for Bebo, unloading it for a pittance of pocket lint last year. Yahoo! (Nasdaq: YHOO) was in talks to swallow Facebook whole, but reportedly balked when it came to price.

Microsoft (Nasdaq: MSFT) came close, paying $240 million for a 1.6% stake in the then-fledgling site to lock up global advertising rights. However, cash-rich Mr. Softy would've been far better off if it had been able to acquire all of Facebook given its own stock's meandering ways in recent years.

Schmidt has regrets? Get in line, sir.

And for those scoring at home, surely Zuckerberg will have regrets of his own in four years for the golden opportunities that he will inevitably let get away, too.

Is Facebook peaking? Will you be a buyer or a seller if it goes public in the next year or two? Share your thoughts in the comment box below.

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Longtime Fool contributor Rick Munarriz remembers when social networks were an offline endeavor. He does not own shares in any of the companies in this story. He is also a member of the Rule Breakers analytical team, seeking out the next great growth stock early in its defiance.