My own view on what might have "triggered" the murders on that weekend run more to the cumulative stressors in Kohberger's life.
Lots of people who are into true crime are also into thinking about crime. We even joke here on WS about "writing a novel" about crime and using some of the specifics of real crimes. People who spend a lot of time thinking about crime and studying crime end up knowing way more about crime.
Do such people sometimes fantasize about committing crimes? Yes.
IOW, I think Kohberger had put in hours of thinking about crime, about how people get caught, what he would do if he wanted to go homicidal. I also have a theory that this type of fantasy helped him self-soothe. Made him less anxious. It's well-known that fantasies can reduce uncomfortable or undesirable drives that lead to undesirable behaviors.
In terms of narrowing down why he finally went off the rails (which he may not have intended to do when he used those crime fantasies are part of his personal stress reduction system), I think it's important to look at the structural conditions of his life - in other words, really obvious facts.
He had vastly increased his "opportunity" window by moving out of his parents' home and across the country. I believe he began thinking about peeping, creeping and more while back in PA, but that he was immediately engaged in this kind of "recon" when he got to the dual campuses in WA and ID. The absence, at last, of parental supervision (and maybe even sisterly comment) was achieved.
But it was also a very high stress environment for him. I believe he wanted to excel in school, in criminology. He felt he had loads and loads of insight to offer (why was that? Because he felt he had a criminal mind that he had "turned to the good.") Why do I believe that? Because I've met several people who thought this way and who are criminals (two of them are criminal cops).
When it became clear that he was not accepted in a special group of people (fellow criminologists), he was hurt, outraged and on edge. He wanted to "show 'em."
This state could have gone on longer without him killing but something (perhaps the near certainty of losing his TA-ship) pushed him into overdrive. We don't know if he had targets elsewhere, if that woman in his program who allowed him into her apartment escaped by the skin of her teeth, or not.
So, my thinking is that he resisted certain other stalked targets (and was probably thinking about young women as targets day-in and day-out) and focused on a few other factors that are often spoken of under the topic of "victimology." How does a killer choose their targets?
I think he knew crimes committed in another jurisdiction (than where one's own ID shows a residence) are less likely to be solved. So he likely focused on Moscow as his fantasy crime target. I think he had shifting targets in his mind and may still have been pondering exactly who to pick on that night in November. And here's where this thinking has led me:
The murderer was filled with anger and resentment at a particular situation and particular targets. Specifically, he was jealous of the free and easy, ordinary college life of 18-22 year olds, especially ones regarded as beautiful, handsome and popular. I believe he had been to the party scene in Moscow and found himself (once again) on the outside. He likely was unable to focus on his own interpersonal skills as part of this; there were real barriers to being accepted by undergrads because...of his intensity, and his actual age. He may even have pictured university life to be a more...academic experience. What he found instead was tons of underage drinking, superficial silliness on weekends, junk food eating, general partying - and probably, quite a bit of sexual license.
But even among these (to his mind) bacchanalian students, he was unacceptable. Even when drunk, sorority girls ignored him and turned to others. He could not find the magic way that other young men had of entering fully into university society and so, he was very angry at university society and part of his motivation was landing blows on that very society.
The victims in this crime go beyond the murder victims. I don't think Kohberger is the type who spends a lot of time in compassion towards others or thinks about souls or the value of human life. The dead are dead. But the families live on.
So, part of what snapped in Kohberger lashed out at parents and siblings of his victims as well. This includes his own family, whom he made into victims and, well, pariahs. He hated college students, young beautiful blonde women (see Elliot Rodger manifesto), hard drinking university students, undergraduates who weren't working hard/struggling to do their best (as he felt he had done). He hated the families of these people - and somewhere inside, he also hated/hates his own family. Mom is massively anti-death penalty; her son goes to a place that has the DP and commits a DP crime (with no insanity defense available). He struck fear into the "party types" across America. He also committed his crimes in a small town; he struck fear into people in less urban places everywhere (like the killers in "In Cold Blood").
He terrorized the college age community and I think the affects are still there (there are maybe 10 online forums about this crime, most of the participants seem to be college age - and I'm sure I haven't counted all of them).
He did this in the midst of an interesting cultural transition in the US (fewer young people are getting married; fewer are having sex; women in particular are having less sex/planning not to ever marry/ planning not to have children). Men are expressing frustration and anger (and entitlement) about this situation every where I go (including my classroom - I'd say that nearly all the men say they won't consider a serious dating relationship with a woman who does not want at least 3 children - preferably more; meanwhile the women have been adamant for the past 20 years that with rare exceptions, they want only 2 - and right now, 20% say they want zero; the men and women argue pretty intensely over this).
Like Elliot Rodger, Kohberger had reasons behind his various targets and I won't be surprised if we eventually learn he had alternate targets (I think he's planning to talk about all this once the trial is over - at least to a criminologist; he may want co-authorship of articles as well).
IOW, there were both personal/structural issues coming to a head; the limits of his already-envisioned plan and already-chosen fantasy targets; PLUS there's an ideological thing going on as well - his targets are not merely personal, he thinks he's some kind of activist. I don't think he charged into King Road with this activism in the forefront of his mind - it's in the background. I do think the troubles at WSU that week/month led directly to him losing it right before the students started trickling away for the holidays. I think the students on King Road were in some sense "stand-ins" for the students he hated back at WSU and also that they were stand-ins for the life he never led and the women who wouldn't have him.
He had envisioned a whole new start in grad school (doesn't everyone?) and felt grad school gave him a Badge of Honor that would trigger a better social life than what he'd had. Instead, he still felt helpless, disoriented, and misunderstood. He likely used the same psychological techniques to amp himself up that he had been using for years in his creeper/stalker phase.
ALL my own SPECULATION and hoping some find this readable or a place to jump off of - as we wait for what is likely to be a trial postponed and a lot of months of very little new information.
TL;DR. Kohberger felt entitled and inadequate; developed real hatred for undergrads and women; acted out for reasons we can only guess at.
ksltv.com
. He’s a true narcissist ... is willing to destroy everything and everyone around when feeling hurt or rejection... Moo 
