Sometimes a good guy with a gun becomes a dead guy with a gun. Right?

When person is intent on a shooting spree or amid one and spots someone w/ a gun, that person becomes the target.

yes.... and sometimes (quite often) a person who claims to be educated, tolerant and TOTALLY against bigotry turn out to be anything but....

know what I mean there, lassie?

Unfortunately, that has a high chance of happening. 

It's understandable if someone wants to try to intervene and help people, but if you have a gun in your hand the police (or other wannabe hero bystanders) have ZERO way of knowing you aren't the bad guy and they have no time to pause and decide first.

Wannabe heroes are better off acting in helping guide others out of there and see them to safety. Let the cops take down the bad guy.

Most good guys with guns kill somebody in their own family rather than a bad guy. Unfortunate, sad and true.

If you have a gun you are NOT a good guy

At least they have a chance. 

Wrong. Good guys don't have guns, unless they're cops. 

Yes, you can be shot in the act of trying to intervene in a shooting, whether you are armed or not.

That said, one has a better chance of intervening successfully  if one is armed with a firearm.

Then you don't have to wait for the shooter to be distracted or run out of rounds to act.

As with any action where your life is in danger, stealth will greatly improve your odds.

No guarantees in the world.

When someone is chopping thru your door with an ax, "who ya gonna call...." Ghost Busters or the cops?

I'd rather be a dead good guy with a gun who went down fighting than a dead good guy without a gun who get executed by an urban person without putting up a fight.