I think the better question is why not seek out some formal training? Depending on your specific choice, it doesn't have to be expensive and these days is available in most areas (or within a reasonable drive) I'm about 15 yrs into daily carry and only
after some formal training did I realize that I was probably ill prepared. I learned more in my 1st day of proper training than I did in a year of practice on my own. My mindset was good but I lacked the physical ability to shoot
quickly and accurately under stress. There are reputable trainers and good classes around that don't cost a lot.
Fast forward to present day, and I Recently took some more training to learn to work around some injuries and a shoulder surgery. The cost: $160 plus a few boxes of ammo for the day... Dirt cheap for the tune up and help to stay physically able to use the gun if needed. The added benefit was that the training was fun and I met some great people there.
I won't argue that mindset is key, but I think all people will benefit from formal instruction or training, and should seek it out as time and funds permit.
