Why do people on HN discuss the title, and not the content? The average discussion on reddit/programming (for example) is now of higher quality than HN these days, for the same story - and with less oneupmanship.
To me, the interesting thing about this story isn't the presentation of the thesis (using Ayn Rand), but to question the thesis itself: Is success more circumstantial than personal? http://nymag.com/arts/books/features/52014/index6.html
The hockey player example creates a subset of advantaged people (i.e. those born nearer the start of the year), for which evidence is claimed.
I'm not sure about the "rice fields" causation, but I have observed, and it's well known that students who are culturally asian study harder. But again, "asian students" is a subset of all students.
In contrast, Bill Gates and the Beatles are subsets of one each. What about all the other bands who played Hamburg (Ringo wasn't there anyway)? Was there a wave of "Hamburg" bands?
And what about all the other kids who had a computer lab - for one thing, Bill wasn't the only kid in that school.
Circumstance (obviously) can provide providential assistance - though it's worth noting that the aid given in all the above cases was not a gift, but more work. And I certainly agree with that - skill comes from practice.
It might be that your potential is set at birth; and there is nothing you can do about it - you cannot affect it in the slightest, no matter what you do or how hard you try. But there is no way of knowing what that potential is... except by practicing as hard and as long as these guys did and finding out.