I have to admit, I was going to post this - but it's probably a very polarized opinion.
The thing is, people do love the idealistic idea of every man creating his own luck - or that if you just work hard and smart enough, the sky is the limit.
When I went a top business school for my MBA, I'd say that 70% of my peers had the same upper middle-class upbringing. Back then, the vast majority went into consulting or banking, and are by every measure successful.
Ten years later and I now work in the startup industry, and it's mostly the same type people I went to b-school with. Not _wealthy_ people, but in the upper echelons of middle / upper middle-class.
I'm not even talking about the "small loan of a million dollars" or trust-fund babies, but just being born into a financially secure family, that pushed you to get a good education, which in turn led you to a good job, and a decent network.
I've lost count on how many ex-McKinsey, Bain, and BCG consultants I've met in the startup scene. People have this idea of entrepreneurs as your garage hacker, or avg. HS / College kid that came up with some neat solution - but from what I've seen, it's mostly kids from top schools, or ex-technologists, bankers, consultants, etc. from top companies, with the same socioeconomic and academic backgrounds.
Not at all disputing list that Sam wrote - lots of the people mentioned above do share these - but I think it's healthy to point out that some people have a clear advantage over others, even in the allegedly _meritocratic_ world of entrepreneurship.