Stipulated. Some people do die because they can't pull the trigger. Training isn't a panacea.
That's not every loss, though. MANY people start behind the curve because they didn't see trouble coming and then exacerbate it by trying to draw on a drawn gun. They don't know about reaction gaps, pre-attack indicators, the whole "left of bang" concept, etc. People pull a gun, pull the trigger, and didn't chamber a round or didn't get the safety off. They go for an off body carry gun under direct observation and lose the race. These people were willing to fight, they had the aggression part, but they lost because of a lack of technical ability.
Nobody has claimed that aggression isn't required and I'm sure you already recognize the false dichotomy. I'm sure you've seen me post "speed, surprise, violence of attack" sort of things before. I'm not even claiming that training is the biggest predictor of who wins fights, just that formal training demonstrably increases the odds of a given population of prevailing. If we don't believe that to be true, why do we bother training cops and soldiers?