Human nature is extremely vulnerable. I'm thinking of one's inwardness, and the way a seemingly small rejection, loss or blow of some kind can be enough to unravel a person's entire equilibrium.
You can compare yourself, even if you're basically a coper -- many people aren't -- to the seemingly impregnable 'Death Star' in "Star Wars". That massive circular spacecraft/world is perfectly defended. Except, yes, there is a vulnerability. It is a tiny one, but it's there just the same. All Luke needs to do is find that opening, and one small rocket is sufficient to blow the entire thing "Sky High" (Jigsaw, 1975).
This cast understands most people as balancing their lives, both inwardly and outwardly, as if they were Charles Blondin, the celebrated French tightrope walker. At any point, we can get distracted or interfered with, lose our balance, and go plunging to our death. I believe we are sometimes closer to the edge than we think.
There's a rather "arty" Hollywood movie from 1964 entitled "Lilith", starring Jean Seberg and Warren Beatty. It takes place in a private psychiatric hospital, and almost everyone in it has fallen or is in danger of falling... over the edge. Two characters actually do. At one point, a character played by Peter Fonda (R.i.P.) asks Warren Beatty, "Do you think insanity is really just a form of unhappiness?"
This podcast, entitled "Susan", actually ends on a hopeful, religious note. And the song excerpt at the end... well, it's pure joy. LUV U.