The author would actually say its the exact opposite(my interpretation). That your focus has been narrowed, creativity would drop, as you have set your sights on the doubled salary, not the actual teaching. The book gives many good examples, that absolutely rang true to me. What you describe, the author spends page upon page explaining why he thinks its the exact opposite. I would say a major premise of the entire book is based on this very example you give. Before I read the book, I would probably have responded EXACTLY as you are. Read the book, it talks EXACTLY about this. I cannot do the book justice, I have only read it once, it will likely be a book I reread every year.