What about the people who dropped out of college hoping to be the next Bill Gates or Richard Branson and failed? These guys are now part of the statistics shown on the graph.
Bill Gates was successful and dropped out of college. He was also hard working and curious. Does that mean that everybody else who's hard working and curious will be as successful without a diploma? I wouldn't bet on it.
Also, having a desire to be in the right place at the right time doesn't guarantee that you'll do just that.
I agree that having a diploma is not what is going to make you successful. But at least, it gives you better odds to beat economic troubles, which is the point of the article.