The latter, probably. People fundamentally do not handle horror and atrocity well, no matter how eagerly they dive into it or how loudly they beat their chest and bay for blood. It's something inherently corrosive and destructive that can't just be warded off by being a bloodthirsty fascist genocidaire.
I struggle to articulate how absurd and evil it is, that they're eagerly destroying themselves just to spill more blood, just to slaughter and spread terror and death and misery for the sake of monstrous fascist ideals. Self-interested evil is horrible enough, but they're beyond even that, it's just death and horror for the sake of death and horror and fascist supremacy. All they have to do is not fucking do that, it's in their best interests to not fucking do that, but their twisted fascist ideology demands they sacrifice themselves for the sake of genocide.
I'm saying that's not a shield against it. Genocidaires dehumanize their victims and they still get fucked up by their own actions and what they're taking part in. It's not about morals or consciences or anything like that, it's just people not handling that sort of violence and horror well at a fundamental level. That's not to say "oh it makes them sad, it makes them unhappy, it makes them regretful" because it can just as easily make them worse and more violent and unstable, it's just to say it's something that actively attacks and corrodes their own humanity. They can psych themselves up and dehumanize their victims and beat their chest as loud as they want, as loud as they need to to push themselves to actually do it, but they're still going to be broken by it in some way.
This isn't something original to Israel, obviously, though that provides a very clear and visible example of a population trying to keep themselves whipped into a bloodthirsty frenzy and breaking at the seams because of it. I know it happened to the Nazis too, and that there's research on that and how Nazi ideology tried to recuperate that self-destruction through violence by lionizing it and making it a pillar of their ideology. I'd assume it's just a universal phenomenon, that such violence just kind of does that to people regardless of how they try to psych themselves up and cope with it.