I believe it's ludicrous to say a pistol is only necessary in certain situations and with certain people.
If someone were to point out the specific situations and persons, that will threaten my life, I would certainly carry in those situations. However, no one being gifted, and knowing by whom and when, your life may end, means you have to simply be prepared always.
I carry at family events. Not because family is a problem, but because I cannot predict who else may decide to join us. My family has my back, and I trust them to be carrying also. We care for each other.
It has already been stated that criminals are taking advantage of a situation and a perceived weakness in an individual or situation. I consider situations where it doesn't seem threatening, to be ideal places for bad to happen.
Predators don't want a fair fight; they want you incapacitated either by pre-occupation or by force. I don't give them the chance. When you have the least reason to worry; worry, and be vigilant.
If you are going to "die", go on your terms not some thugs.
"Peace is that brief, glorious moment in history when everybody stands around reloading". Anonymous
Earp: Not everyone who knows you hates you.
DOC: I know it ain't always easy bein' my friend....but I'll BE THERE when you need me.