More people are sane than are crazy. I live in a major city in Texas and I like that the mostly sane people around me might be carrying.

I see it as a type of herd immunity against people who are actually crazy

Basically you are saying that you like the power balance between the crazy and non-crazy. Which is quite dependent on the definition of “crazy” and does not depend on the _level_ of power. One could have roughly the same balance with very limited weapons available as well as even more and more powerful weapons being carried. It’s interesting how societies decide as to how to achieve that balance.