I don't mean I liked the story but I share your opinion.
Not to drag us O/T again but... as a person with mental health issues (bipolar II) I can tell you that when someone is genuinely suicidal it isn't "my life is ****" or "if I do this then everyone will feel bad about how they treated me", it is (or was for me and others I know) "I'm ****, I fail everyone who needs me and the world would be a better place if I weren't here hurting people" - not at all logical, but the view you have of yourself is so warped that you can't see how your death could possibly be anything but good riddance.
For me, nothing would trigger it - wasn't anything anyone said to me or anything that happened during the day, but after a time of crazy happiness or high anxiety this horrible weight would descend with alarming speed, and within an hour I'd be trying to end it all. After medication went somewhat disastrously (paranoia, blurring of reality etc) I ended up developing a "survival kit" which I can honestly say saved my life.
So while it might seem completely senseless and selfish to those looking on, mental illness twists everything and genuinely depressed people (not drama llamas) are in a personal hell that only they can see.
(Sorry mods, just thought I had a duty to weigh in on the matter
Back on topic, not exactly a bad habit but people riding when they're in a bad mood really annoys me - they get frustrated and either quit at the wrong point or take out their mood on the horse. I generally see this with spoiled kids who are too obviously being pushed by their parents, or people who have forgotten why they liked riding in the first place and have developed an obsession about winning ribbons at all costs.