"I've trained over 3000 people this year" ..... :gorilla: Maybe so, but I wasn't one of them.
Each of us have our own preference when it come to firearms and ammunition.
A specific individual may shoot a certain caliber with more accuracy than another, thus achieving better results.
I currently shoot .380, .9mm, .40 and .45 in my pistols, but do not preach on one specific caliber, or force it on others.
Ease of carry and the overall weight of a pistol comes into play when you're speaking of concealment, for the average citizen.
There is a lot more to ballistics than caliber size. As in, despite what you have heard, bigger is not always better.
The .40 is a heavier round than the 9mm giving it some of the advantage of the .45, however it does not sacrifice velocity to achieve the higher weight unlike the .45. In most situations it is more a matter of where you hit someone rather than what you hit them with when it comes to handguns.
According to the FBI the only things that matter (ignoring shot placement), are whether or not your chosen round will penetrate enough and how big of a hole it makes. Whether you choose a 9mm, a .40S&W, a .45ACP, or whatever to accomplish that goal, I don’t care and I really don’t think it matters all that much as long as you can handle your chosen weapon/caliber combo.
Just my 2 cents.