I grew up with guns, both handguns and long guns. I had a carry permit for many years when I need it and spent many hours and $ on the range to sharpen my skills. It would take a rather skilled combat shooter to step up in an active shooting situation and take out the criminal without wounding innocents. When one trains for a carry permit you learn not to shoot unless you have a clear shot. For a civilian in a situation with elevated adrenaline levels this may be impossible. Defensive shooting comes with other drawbacks. How does LE accurately determine who the good guy with a guy is in a matter of a split second. Combat veterans may have these skills. Non combat veterans may not. Headlines show us the number of LE who react too quickly and erroneously when it comes to shooting civilians.
FWIW I no longer need to have a carry permit and keep a classic Rossi .22 single shot long barrel for target shooting.