wmboy made a good analogy in a another comment to abs.
Most people can be thin/muscular/athletic and most want to be. Many try and of these, most fail. But, this is fundamentally different from an aspiration to be in the olympics. Most people can't do that, regardless of how hard they try or how strong willed they are.
I'm not sure the Olympics are a good metaphor for Facebook's success. The reason a person like me will never be in the Olympics is a lack of physical talent. People who have that talent, if they work very hard, have a realistic shot, but it's less (probably much, much less) than 1/10 of 1 percent of people for whom being an Olympic athlete is even an option.
By contrast, I think at least 1 or 2 percent of people have enough talent to do what Mark Zuckerberg did. He's a talented businessman who has done a lot of things really well, but I haven't seen him do anything I couldn't have done in his position. The odds are enormously against that kind of success no matter how smart you are, but the minimal level of talent to do that is not that rare.
I'm sure the metaphor can be tweaked to be more accurate in representing the mix of talent, luck, mentality, etc. (it's also the case that not everyone who gives it an honest shot will succeed at creating a 10k business while virtually everyone who diets and exercises will get slim an muscular)
The point is no so subtle though. One is in reach of most people who will give it a shot while the other is exceptional.
Most people can be thin/muscular/athletic and most want to be. Many try and of these, most fail. But, this is fundamentally different from an aspiration to be in the olympics. Most people can't do that, regardless of how hard they try or how strong willed they are.