I knew in high school that I wanted to become a surgeon. That made the career decisions of the next 14 years of my life pretty straightforward. I had to go to college, then to medical school, then to my internship/residency, then into clinical practice. Doing medical research would be interesting and also help my chances of reaching a top tier location for each of these steps. That part of the decision process was already done. All I really had to do was work really hard and decide was where I wanted to go among my available options for each step. Deciding on academics versus a group private practice versus a solo private practice seemed like such a big decision, but in retrospect these decisions, while important, were quite limited in nature.
In contrast, the search for a new career can seem like the game where you run in circles with your head down on a baseball bat and then try to run to first base, only to stagger toward third before falling down.
In most careers outside of medicine, the opportunities for your future career become less predictable and structured. This possibility can be intimidating to someone who needs a well-illuminated path ahead of them. These individuals can fall back into a fairly linear path in their new career and be successful in that regard. Other individuals may see the endless career options as the ultimate opportunity. Not knowing where they will be at a certain point in time provides limitless options. They keep their eyes open for opportunities, accepting that they have not calculated the plan in advance.