Or, as pointed out in an article cited, a person is sufficiently, if not exceptionally, proficient but is simply ill-suited:

"I was in the throes of a brief, doomed romance. I had attended a concert that Saturday night. I answered the question with an account of both. The guys stared blankly. Then silence. Then one of them said: “I built a fiber-channel network in my basement,” and our co-workers fell all over themselves asking him to describe every step in loving detail.

At that moment I realized that fundamentally, these are not my people. I liked the work. But I was never going to like it enough to blow a weekend doing more of it for free. Which meant that I was never going to be as good at that job as the guys around me." - https://www.bloomberg.com/view/articles/2017-08-09/as-a-woma...

This is often how I've personally felt.