I think (and it's just my theory) that when we say there is nothing we could have done to prevent it, that's accurate because even if a situation triggered it, removing the situation doesn't change the risk of it. This goes back to Changing4Ever's last statement, which I also believed for a long time (we were having huge financial issues, family problems, etc., and I assumed everything would be better once we fixed the outer things).
But the underlying issue (chemical impairment, genetics, or psychological predisposition) still exists. There's a reason the trigger made them behave this certain way. But also, like with bipolar mania, it's not inevitable - once you understand the risk, you can, not control it, but at least be a better predictor of what triggers it and/or what signs show it's coming on so you can take measures to ease it.
That's not a perfect science, but I am hopeful that one day, if we recognize this as a 'thing' that is more than just a punchline, a plan of action for the individual can be taken to fit their unique needs, and turn from crisis to transition. My own crisis didn't 'stop' until I changed nutritionally (supplements that regulated serotonin and dopamine) and delved 100% into a plan of personal and spiritual development. I don't think there's a magic pill that just stops it, but if it was seen as a disorder, the shame factor could be lifted and treatment for the individual could be developed.