Has a fighter ever been injured by refusing to submit when in a submission hold?

No such thing in regular boxing. Never done any of the other stuff. In a regular fight a tire tool will take them out fast. It’s happened to me ; ). Luckily no serious damage done.

In a real fight, ever? What do you mean by asking that? Are you asking for an example?

Yep, I have seen it many time in BJJ.
Specifically, broken wrist, broken ankle, sprains, and just plain passing out.

@Zaku Yes. wondering if it is a false pain, that one can ignore the pain and keep resisting. Yes I would like an example.

It has happened many times, but not always, of course.

It depends on what lock is used, and what they do after the person doesn’t submit.

I looked for some good links to specific examples, but ran out of willingness to search for those after finding many articles on related topics.