That is your personal assessment of your capabilities, it does not necessarily reflect the capabilities of everyone; therein lies the problem.
In the case of firearm policies many that think they are right and anyone who does not ascribe to those views are portrayed as you did in the above assessment.
Now I am not saying that everyone who wants a firearm should have one and again therein lies another problem. Assessment of determining what laws should govern firearms should not be based on the few but on the majority.
To your personal observation of your capabilites might surprise you in a actual situation. You say you have had simulated combat situations yet you think you could not react correctly in a real threating situation. You might be surprised what you are capable of. It is possible that your training, no matter how far in the past it was, could control your actions. Then on the other hand it might not, you never know what your capable of until you are placed in a situation. But of course constant training always improves ones skills, but once a skill is learned that skill is always embeded in your subconscious no matter how "rusty" it is. Then again the ability to use it may be overwritten by other mental "programs".
The chance of a priviate citizen being placed in a situation where the use of a fiream is called for is very very remote; however even though the chance of that occuing has a very low probibility of happening it is not impossible. I don't how I would react in a life or death situation now; however I would prefer to have the option of having the means to react. However, I would really prefer to never have to find out.
The chances of being places in a situation where I would have to use a first aid kit is vastly less remote than the probability of having to use lethal force against another human being; yet, curiously, you see very few people espousing the pressing need to stock up on necessary first aid equipment "for protection", and the entire issue is far less embedded in identity politics and ideological rhetoric.
To be perfectly honest, I think that in a modern post-industrial society, the actual, material necessity of carrying around deadly weapons is usually miniscule to nonexistent, and that people invest importance in personal firearms that is far out of proportion to the number of potential use cases of these things in their everyday lives. And I get the impression that at least in America, the ownership of personal firearms has become embedded in identity politics to such a degree that no amount of rational argumentation could shift people's opinions on the issue in either direction.
I agree that there are those that carry firearms, especially those that open carry in public, ascribe to your views as expressed above, however do not judge all of us in the same manner.
Ironically, I'm actually far more puzzled by the vast support for concealed carry practices in the US. I can at least understand some of the logic behind openly carrying a firearm, even if I do not share it; and I would argue that there is some utility in knowing whether a person is armed or not. But I can't wrap my head around the logic of purposefully hiding the fact of being armed with a lethal weapon.