Not going to get into whether the holocaust happened or Katyn or any of those. It’s pretty clear what Caligula got up to so let’s do him.
When it becomes clear you’re dealing with a monster who will kill you all, why do you not eliminate the threat?
a. You yourself have a cushy position that, if you lose it, you’re in a bad place.
b. Were you to kill Caligula, Ilse Koch or Irma Grese, the chances you would be gruesomely and slowly murdered in unspeakable horror, by the rest of them, would be high in the mind. Taking out an Ilse Koch and hubby leaves all those other officers to take you or your children out.
c. It’s possible that you would never know what they’re doing – you’ve been kept apart and they never speak of these things, either through cunning or as a way of handling what they were doing.
But let’s say you were in a position in Caligula’s household and he has made everyone an enemy, in fear for his/her life, and you suddenly find the opportunity.
What’s uppermost in the mind? Altruism for the rest of the household or for Rome? Or self-preservation for you and your family?
I’d suggest that these days, the issue is a bit easier.
The way it was dealt with in my long book was that they took out the top floor of the Masonic Temple with a missile on a timer, once they were safely offshore.
The victim also died, as did some of the hall staff, but it did take out the principals, who were oppressing the people as a whole.
In Caligula’s time or Nazi Germany, it seems a lot more fraught.