The best book I read this year was actually this (https://www.jstor.org/stable/10.5325/j.ctv2321hnd), so I'm aware (and was aware before) of human sacrifice.

Rally round the flag accounts for "violence done by others against us" and not "random violence against ourselves" so I think it's completely meaningless in the case of this conversation.

With regard to human sacrifice, how much violence have you been involved in? Maybe a few fist fights in middle school or high school? Do you know anyone who has committed real violence? I'll bet you don't. It's exceedingly rare these days compared to historical norms. People might disagree on why its become so rare, but the general rarity is a fact. Even for areas with high violent crime, there is usually a small minority of violent re-offenders, rather than a large majority of people committing random violence.