It's no secret "it’s hard to be totally happy/fulfilled in life if you don’t like what you do for your work." The point is "most people pick their career fairly randomly"; to those people, the rest of the advice he gives in #4 is very helpful.
Napoleon Hill would certainly approve of the suggestion to "aim to be the best in the world at whatever you do professionally"- similar to the philosophy Hill promotes: "Whatever the mind can conceive and believe, it can achieve regardless of how many times you may have failed in the past". Unless you were born into a billionaire family and never had to consider goals of the people around you, I'm sure you're aware that most people, even in America, unfortunately, don't believe in themselves very much. https://www.forbes.com/sites/niallmccarthy/2016/09/23/survey...
Even ambitious people tend to set goals way lower than they are capable. A person working all day every day to make a million dollars by retirement could probably make a billion in 10 years if they believed it.