We tend to make a lot of assumptions about how people do or do not behave under stress, in a gun fight, after they are shot, and so on.
The “normative assumption” or “presumption of rationality” is the tendency to expect that other people will behave in a reasonable, logical, or rational manner in a given situation. This assumption often leads to misjudgments when others act in ways that are irrational and unpredictable.
This can result in poor tactical and strategic decisions.
You will never be able to understand what motivates some people, or the logic behind their behaviour, and that’s fine. Always leave part of your mind open to the possibility that things could go pear-shaped in an instant.
The gentleman in this video, for example, is completely irrational. You will not make sense of his behaviour. He will not respond to reasonable directions. He is not acting in his own best interest, he is not even responding to a gunshot wound to the chest the way you would expect.