That’s how Malcolm Gladwell described Bill Gates walking into his highschool in 1969 and finding they had a computer terminal that students could use.  The quote is “He had this one in a billion chance to get good at programming in advance of every single member of his generation.” (In an interview played on National Public Radio’s All Things Considered this evening.)
This, of course, annoyed the hell out of me.
First, how many people were there at that highschool? The opportunity was not unique, it was at the very least available to a few hundred or a few thousand students at that school. And even considering the whole population of the world at the time, it’s a couple of orders of magnitude less rare than “one in a billion”.
Second, I had a very similar situation. My highschool had a computer in 1968 (not just a terminal), and that’s where I started programming. I also had access to a similar computer at Carleton college, and a few years later got access to a different computer at St. Olaf college. And in fact in 1969 (when I was 15) I was hired to write computer software for Carleton.
So we need to include all the people in my highschool into that count. And I imagine there are several more worldwide; leading to a total of thousands or tens of thousands of students who had access to a computer in 1968 at about the same level Bill Gates and I did.
And very few of those people are titans of the software industry. Most of them aren’t even in the software industry (I am).
Certainly opportunities are unevenly distributed, and play a major role in what people get to do with their lives. But very often, when you look carefully, the opportunity is not as rare as you might initially think; and the probable importance of hard work and choice by the individual thus becomes greater, not less.