They aren’t interlinked in the way you think.
People who have the temperament to perform at the upper echelons of their discipline are *more likely* to suffer from mental health issues as they work in high pressure environments.
Your logic is floored. You are assuming that people with mental health issues are in some way weak. But mental health can be impacted by lots of different things. The loss of a parent or child, a divorce, financial issues, age etc.
Those kinds of things can affect everyone. People have different capacities for stress (I mean that in the broadest term and not just work stress). irrespective of your capacity there will be moments where you your limit and your mental health is affected.
It’s part of life, it affects EVERYONE, irrespective of what you do as a job. Irrespective of how successful they are.
Successful people are successful because they have the ability and the temperament to get there.
You don’t become a surgeon without the ability to work under pressure and the conviction to get to that level of expertise or the intelligence to absorb the level of knowledge required to cut people open. But that does not mean that a surgeon cannot have mental health issues.