Yes, the idea of mental illness can freak one out, there's a lot of stigma that comes with it initially.
But once one learns that a lot of people have the same issues when they push past their limits things become easier to handle. It can even become a telling episode of how not to abuse oneself by accepting stressors that are not worth it.
I don't get where you get that idea. I'm in no way saying "only mentally ill people thinking killing themselves". What What I'm saying is that from time to time we all find ourselves with poorer mental health and we can learn from it.