As far as the Foreign Service experience goes, you're in a strange country where you often don't speak the language so everything is difficult. You may not be well liked, or worse, may be hated, and people may be trying to kill you. The opposition security services openly tail you wherever you go, bug your house, your telephone, and on top of that, your own CI people may be spying on you. The pressures to perform at work for Foreign Service are enormous, since (unlike the civil service), if you don't get promoted in a specific time window, you're fired. You work in a fish bowl, and cliques form mainly of effective people vs the dumb ones. It's extremely hierarchical, and if you're low on the totem pole, and you're ineffective, you're ignored and left out of the loop.

Often the security services routinely surreptitiously break into your house and rearrange shit in your fridge, or other head-fuckery, just to intimidate you, and just to show they can.

It's extremely difficult for people who aren't prepared for that environment. The ones that crack are usually civil servants overseas for the first time for domestic agencies like IRS, Social Security, FBI, Commerce, etc. Most larger embassies and consulates have a State Department shrink working there, for good reason. People lose their shit all the time. It's not particularly rare.

Additionally, in the more difficult countries, you are essentially living with the people you work with. That can induce some particularly cruel claustrophobia.

So, it's no wonder people are driven mad, either by each other, the environment or just crickets.