unpleasant theory: maybe in some cases it is even better, that a person just kills himself after a drug-triggered insight - instead of years of drowning everybody around them into their black hole - and still suicide in the end. (or worse, go amok)
But sure, I am not saying at all, that this was the case in your story. What I know is, that Psychedelics are no miracles. The "insights" you get, might be also totally wrong and misleading.
I see Drugs as "tools" for the mind. You can use them right, or wrong.