I hope this is the right place to post this question.
Often in Japanese media or some other medium I often hear a person saying to another person "I WONT FORGIVE YOU!" Now this would not be confusing if that person said it to someone who might actually care if they are not forgiven like a family member, friend, etc. However I often see it directed at someone who obviously does not care. Why would someone scream that at an who is usually the/a villain. The person is already doing horrible things to you. Why would you say you wont forgive them when it is certain that they don't care. This sometimes is even directed at things that are not event sentient, like a giant monster or robot. What is the cultural meaning/reason behind the phrase "I WONT FORGIVE YOU!" If this has been answered in the videos I have not seen it, and could you please direct me to that video.

Never hear it in real life in Japan.
Sounds more like an inaccurate translation of something else.

That's a lot of mistranslations then, and I mean a lot.