Great question and responses in the thread as I think/hope most here hold life sacred. I agree with those who wrote, the object is not to kill but to stop an aggressor from using lethal force against me or mine. Plain and simple. There are those who do not hold life sacred and would, in an instant take an innocent life. Happens every day somewhere. I am not one of those, will never be one of those and would like to die in my bed as an old man of natural causes.
Downside is I'll more than likely be reacting to that aggressor's action and be behind the power curve to begin with. Thus, practice, practice and maybe some more practice would seem to be prudent, hoping I'll never need the skillset or cross that particular bridge.
The old adage, "I'd rather have it and not need it, than need it and not have it" rings true for several things (e.g., life saving first aid, fire extinguisher, etc).
Like others, I do find that carrying makes me look at issues and places with an eye to avoid with somewhat of a different level of situational awareness, than, say, my mother or sisters, who have told me more than once they could never, under any circumstances, utilize a firearm for their own self preservation or that of their family. (sad that... perhaps) Both have been in situations where they were scared witless yet hold fast to their belief. They did not, could not believe me when I told them of Warren v. DC and Gonzales v. Castle Rock. Such is life.
Chances are, whatever handgun I carry will never be needed.
I hope.
YMMV