And a lot of practical experience. A person needs to get the mindset of carrying what they might really need, not what is the most handy. A 2 shot NAA derringer is better than nothing but a bad guy with a Glock will make short work of that idea.
And there are a LOT of bad guys out there with Glocks.
I was talking to a peaceful 45 yo Jamaican guy I know the other day. He told me that every brother in the hood has a Glock, good guy or bad guy.
Slaves get what they need. Free men get what they want.