And I disagree with your sentiment. When people think that X, Y and Z will lead to success and they do X, Y and Z and they fail, that produces a mentality of failure and frustration and why people give up.
Understanding what success really is and how hard work, contacts and luck play a role in it actually frees people to take risks and try again and again. Unbridled and childish optimism is why so many people fail and that leads to a mentality of failure.
And no. Sam's advice isn't necessary nor sufficient for success. There have been plenty of successful people ( extremely successful ) who didn't follow his advice.