Two quick thoughts........bad guys are not afraid of guns as much as they are afraid of resolute citizens who have made it clear that if the transgressions do not cease, there WILL be gunfire. In about 90% of the occasions where a defensive handgun is displayed, there is no need to shoot, it ends right there.
The second thought is that if you're confident with your sidearm, you will prevail. Just remember that if you HAVE to shoot, keep shooting until the threat is OVER. But in the vast majority of incidents, just having a gun is half the battle! Nothing beats good practice and confidence with your weapon! Just the same, I carry backup ammo, and lots of it. Better to have it and not need it.......
I'm limited to a 38 on duty, but I shoot several times a month, and have a lot of faith in my ability with my poor old antique Smith & Wesson Model Ten. It wasn't obsolete in 1961 when it was made, and it still isn't. As the old timers say, "It's the singer, not the song!"
Papajohn