A self defense shooting in a home where it's pretty much you and the perp is one thing, but in a mass shooting event it's totally different. Lots of collateral damage where trigger happy cowboys all of a sudden thrusting themselves into the role of John Wayne is totally different.
A big part of the problem, is you, and your concept that everyone carrying a gun is thinking they are Rambo or John Wayne. Yes, there are some, but they are the exception. In short, you have listened to too many people that don't know what the fuck they are talking about.
All the people I know that carry, do so for one purpose... to go home at the end of the day. Unless you live in a state with very restrictive laws, you would be surprised how many people you see out and about are armed. In NC about 6% of the population have carry permits.
Virtually every shooting in the news is by a criminal, most of whom are not permitted under law to even own a gun.
"We", those that can legally carry, are not the problem. The number of people with carry permits in my state has tripled in the last 10 years. The John Wayne shooting of your fantasies... I'm not sure that there have been any.