Not unusual for folks to look at things from a perspective that supports their own confirmation bias. Consciously or unconsciously.
Planning for failure can also be intentional or unintentional.
Folks can attend all the training they can find, but that doesn't mean they've either learned the right lessons from it, or
will be able to apply it under stress.
Time spent in training/practice can matter, but simply burning powder for the sake of being able to tell oneself that they're racking up round counts doesn't mean they're practicing the right things, or the right way. People can get 'better' at doing things wrong, too.
Don't expect significant differences when using any of the modern service/duty calibers, and you won't be disappointed.
Don't assume caliber offsets skillset or mindset. (Or mindset offsets caliber ... or skillset offsets mindset, etc.)
Don't assume high capacity will offset high numbers of misses ... and those misses are going to hit something/someone down range, which is another type of BAD.
Carry what you can use. If there's a difference among your different chosen guns regarding how well you can use the, under demanding conditions ... try to pick a point where you can recognize if diminishing returns suddenly occur.
I've known my fair share of guys & gals with whom I'd go through any Dark Doorway, even if they were only armed with an old S&W M10, or a .380 ... and I've known even more of them I'd
not wish to cover me no matter if they were armed with high-cap pistols and carrying a dozen spare magazines.
You want to bet your life that gear will always make up for user shortcomings? Different strokes.
Real life - and Murphy - are always throwing us curve balls. The bat you choose may not mean the difference when you take your swing.
You don't have to convince others of your opinion and preference. You just have to hope that you're right, willing and able to stand if/when the time comes for you.
In the meantime, enjoy your gun ownership and shooting hobby ... and train/practice like it may matter someday. Because it might. Probably not in the way any of us expect, though.