Still there is a chance that you would be able to do that under lucky circumstances. And that chance justifies permission to carry weapons.
And what is the probability to hit a perfect innocent in these circumstances?
If gunman knew that many people would be carrying concealed weapons, he probably would not even consider such an attack.
You mean like no one is attacking NATO force in Afganisthan because they are openly carrying weapons? If some nuts decide to go mass murderer it is not some concealed weapon that are going to make him change hist mind, he will just use clever tactics.
In my case, I would need to be pulling in well over 200K after foreign taxes per year to owe the IRS. Most normal Americans who work in foreign countries probably won't owe the IRS any taxes.
As the dollar is currently not very high and as other countries have different standard of living 200K can be reached quite easily. Being a MD, Manager, Lawyer, or whatever in upper salary range in Switzerland will get you over 200K easily. The problem is also with the banking system, as the IRS tries to police the world, it's a nightmare for a US citizen to open a bank account in Switzerland, and a lot of Swiss bank just refuse to open an account to American citizen. That's maybe why ceremony of renunciation are hold quite often in Switzerland.
When you don't know what you are doing, do it neatly.