It is comforting to assume that terrible things only happen to people who cause them to happen through their own choices. That is part of what is called the Just World fallacy... and it is a great favorite of successful young people who want to believe that their positive trajectory in life is all due to their hard work, that they have more control over their fate than they actually do. Assuming that those who fail are almost always at fault makes you feel more secure that you won't find yourself on the wrong side of fortune. After all, you have control over the choices you make, and so you can protect yourself by just making the right choices.
But the truth is that there is a certain risk of random bad things happening and that every day of your life, you are exposed to some miniscule fraction of that risk. On any given day, that risk is so vanishingly small that it can be entirely discounted, but the 7-10 years of med school and residency adds up to a lot of dice rolls. There are a number of illnesses, mental and physical, which are especially likely to present during these years. Some periods are more vulnerable than others, like intern year. If you don't finish intern year, you can't get a license at all, even though you completed medical school. Programs do not have to provide an intern who became ill or injured with an opportunity to return the next year. Finding a new internship may not be so easy, if you can't find someone to take a chance on you.
So, if you have your first round of MS, or leukemia, or breast cancer... those don't have to be permanently disabling but they can knock you off the path. Mental health is even more stigmatized, and there are people who will straight argue that a physician with well controlled mental illness still shouldn't be permitted to practice, because what if... Those aren't things that never happen. You just don't hear about them so much when they do, and that helps build your confirmation bias and reinforce your belief in the Just World fallacy.
In other industries, you can get a second chance. Medicine is set up so that if you don't get through that vulnerable 7-10 years more or less on time with very little disruption, you may not ever get to try again, no matter how capable or deserving or whatevs. There are a few periods that are especially tense... like intern year. If you don't complete your intern year, you can't get a license. And you may find yourself unable to locate an opportunity to resolve that, no matter how capable or virtuous or deserving you may be. Residency spots are an artificially limited resource and when there is always a new cohort of fresh grads who don't have a complicated backstory who want them just as bad. Business opportunities are not limited in the same way. Indeed, it is the nature of entrepreneurialism that if there isn't already a job waiting for you that you create your own opportunity out of thin air. Yes, that takes some brains and effort and luck, but if you fail it, you can always go again... there is no limit on attempts, like there is with taking Step exams.
I don't blame you for wanting to look away from the uncomfortable thought that you might, through no fault of your own, have the door to your dreams slammed shut in your face. If I hadn't seen it happen to a few people, I'd rather not acknowledge it either. But you do yourself and those who are in that situation a disservice by pretending that anyone is so virtuous as to be safe from misfortune.
