The running hypothesis (at least in our lab) when I was studying neuroscience was that it was a perfect confluence of epigenetic factors brought to bear on a particularly susceptible population.
In other words, that much pressure makes some people break with reality to escape it.
In other words, Bostonian, I think it's probably both of those things.
You do, however, see the same general phenomena in POW's, so clearly applying relentless, all-consuming pressure to human beings is... unwise... to begin with.
For PhD students, "Stockholm" means a lot more than Nobel. My DH and I have speculated that it's a mark of how non-violent HG/+ people are as a general rule that there aren't more instances of students going postal on their committees around oral qualifiers. It's remarkable to me that it remains quite rare.
The military also does a LOT of heavy-duty mental health screening/stress-testing for high pressure service occupations. My FIL shared some of the stuff they put him through as one of the original Nuclear Sub chiefs/officers, and it is really thorough. So they certainly recognize that there is a risk, and want to carefully evaluate prospective sailors before turning them into nuclear submariners, where the pressure of the environment can serve to destabilize a person with the right set of characteristics. The space program also did/does a lot of psych evals as part of screening potential trainees.
