I disagree with the idea that meticulous caution can only be learned by personally failing first. I believe it is fully possible to learn and emotionally internalize the necessity of proper protocols, rules and behaviors in a variety of safety and compliance contexts by learning from the failures of predecessors, and without needing to commit those failures personally.
If this were not the case, wouldn't e.g. insurance companies weight risk analysis algorithms more favorably towards drivers with an accident history, and penalize drivers with no accident history? (This is a simplistic example, but you hopefully get the idea). Do pilots need to experience catastrophic crashes in order to achieve true risk awareness? Do companies need to experience serious security breaches in order to take security seriously? (Many of the most secure companies in the world, perhaps most of them, have never had a headlining security vulnerability).
To continue with your analogy, I see no a priori reason to assume that a doctor is incapable of following e.g. comprehensive checklists to limit surgical error without first experiencing a failure that causes a patient's death. Likewise, I see no a priori reason to assume the same doctor would improve by virtue of having a patient die in surgery.
I think that claim requires evidence to be taken seriously, to say nothing of your secondary claim that people who have not failed have "too much bravado" to be trusted with responsibility.
With the checklist analogy: some doctors are willing to follow checklists; other doctors aren't. Of the doctors who have killed a patient from not following an available checklist, usually all are willing to follow a checklist—for the ones that still aren't, and kept on killing patients, have been disbarred. "Did a bad thing and is still a doctor" is a sort of survival-bias heuristic for filtering out the non-conscientious.
Here's another way to think about this: a soldier might have trained for years and years, and be very good at all the arts of war. But most people would prefer to staff a "hand-picked" strike force with veterans—soldiers who has been in a number of battles, and in particular have been engaged in a number of individual combats—rather than just people with "natural talent." Because attrition ensures that the only veterans who survive are the ones who know their business.
Personally, I don't believe there is such a thing. The only careful doctor is one who has made a bad decision that killed a patient; the only careful military officer is one who has had a strategy of theirs fail and lost soldiers under their command. Everyone else has too much bravado, and no emotional revulsion to shortcuts, and so can't be be trusted with real responsibility.