Sarcasm is an adjusted stress reaction.

And of course people can find a kind of comfort in dark stuff too -- as a teenaged girl I glommed onto The Bell Jar because it was one of the few realistic portrayals of depression I could find at that point. (There's an interesting echo with so-called "sick lit," modern memoirs about illness, especially chronic ones, where the authors are often bugged by editors to have Happy Endings where they have Overcome All. And if a depressive, say, commits suicide, a lot of the time people are like "oh it's terrible they failed and their life was such a waste." What about all the time they managed to survive? Was that a waste? Bah.) (Sorry, that just gets me hot under the collar and I saw an example of it very recently.) Something doesn't have to be necessarily HopefulTM for someone to find it uplifting or validating.