It is not easy to understand it but some people are just wired differently and there's not a cure for it. They can try, and that's a big TRY, to treat the symptoms but the cause is difficult to treat. The meds are hit and miss and can actually exacerbate the issue.
How can a parent murder their own child? How can someone be a serial killer totally lacking compassion or remorse? How can someone once they've reached the summit, the goal they were seeking, just end their own life? They "had it made"!
There have always been people born with a wiring issue and the stress of society wasn't as prevalent as it is today. Men laughed off PMS as the "blues" or a "bad mood" and Post Partum Depression was thought just to be made up until more research was conducted to prove these exist in some women.
If you consider yourself to have sound mental health and can't understand the "mental health issue", count yourself as a lucky person. While some feign it, it is a real issue for many people and debilitating to their everyday lives.
I have a close friend that is a well respected shrink in Dallas and she told me her most heartbreaking patients are those that are aware they're mentally ill. It is like a waking nightmare to them that they cannot control or wake up from and all they can do is throw meds at it and hope that works.
Just how tricky is the mind? Clinical depression brings about the creation of Prozac, and others, and they discover one of the latent side effects for younger people is suicidal thoughts. I think that's not an acceptable side effect to depression meds.
Honestly, the biggest problem for people fighting mental illness are the people that refuse to consider it a disease. That they can just snap out of it, toughen up or grow a pair. It is OK to not understand it, it is not OK to discount it.