We are, IMO, running a strong risk here of mixing our apples and our oranges.
When we begin to discuss the relative merits of more (and maybe more and more) training, we bring up the specter (most any government bureaucrat will do for this) who will stand ready to define for us who should be allowed to exercise their rights.
Training is absolutely valuable and the more (good) training one can get, the better.
However, I don’t hear anyone arguing that training is necessary in order to defend oneself or others.
We absolutely must strive to be consistent: We have to learn to tolerate those people with less ability, knowledge, intelligence, and, yes, training, doing all kinds of things they should be free to do including; speak, practice their religion, go about the world armed, and the rest of the BOR as a bedrock start.
Of course it can be dangerous to allow stupid, ill-informed, and untrained people to freely carry arms or to speak out in public or to run for office or to vote in elections.
However, IMO, our focus on political correctness and our fears of what some may do with their freedoms has led us down a very precipitous and dangerous path over the past 100 years or so. We as a society have to learn to separate our fruits meaningfully to develop the kinds of arguments that will help educate (and train) those who need it without contributing to the denial of their rights.
Show me the data