The difference between a fear inducing situation and a demanding one is the
recognition that you have the tools and knowledge to manage the situation.
You may possess the tools and knowledge to handle a hairy situation, but if you do not recognize that fact you are in trouble.
Some personalities move early on to panic when confronted with adversity. If you are one of those, then it would probably be best if you do not occupy the pointy end of an aircraft. I do suspect that with deliberate effort, some could overcome an early panic tendency, but it would not be easy.
I am not a psychologist but as a former military flight instructor, I have seen students freeze up at inopportune times.
Their ears stop working, their minds are overloaded, and they keep right on doing the thing that would kill us in a few seconds if I let it go on. As I said, you have to take people out of their comfort zone, then give them the tools to succeed. But first, you have to get their attention.