It's a discussion that needed to be brought up, and I haven't really directly had experience dealing with "mentally ill", people, but I've had periods of severe depression in my life. I don't know if that qualifies as "mentally ill", but it was very debilitating and insightful as well.
Where do you place hallucinations, both aural and visual, and antisocial behavior? Of course I realize that aural hallucinations might be useful for a composer, and visual hallucinations for a painter, and there is always a place in our violent society for anti-social people during wartime or the CIA, or even politics. And it's possible that so-called mentally ill people are just out of context in our modern contemporary, patriarchal society.
Back in pre-renaissance days aural hallucinations might have been considered messages from God or a demon and might have been considered quite acceptable or, at least, normal.
During the Third Reich millions of people considered Hitler and Goering and Joseph Goebbels not only sane but epitomes of mental health and sanity and even saviors. And many people consider Trump to be totally same too.
Mental illness/health is too often misunderstood in terms of cultural judgement. Literally, mental health refers to how you feel, function, and how that is related to mental activity. Defining someone as 'sick' in order to put them down in some way is to mental health what fat-shaming is to diet/exercise management for health.
Health is a major contributor to attractiveness, but that doesn't mean that they are one in the same. If they were, then people who use plastic surgery to look more attractive would also become more healthy in the process. They don't. It's just cosmetic. It's like cheating on exams to look like you learned the material, when in fact you didn't and the whole purpose of the exam was to motivate and ensure that students in fact learned the material.
Behavioral conformity is to mental health what cheating on exams or rote memorization of information is to learning and intelligence. Cosmetics simulate and conceal, and that is what behavioral conformity does with mental dysfunction. Revealing that can be very scare for people who are afraid of mental health evaluations as a form of stigma that will draw ridicule and disdain, discrimination, etc. from others.
So the appearance of mental health can be simulated cosmetically by means of social-behavioral/cultural conformity. Still, mental health does not actually have to do with how you act but how you feel and function. You can be a very independent-thinking individual who others regard as 'crazy' yet be perfectly healthy mentally. Likewise, people might consider you very normal and sane because of how you behave and appear outwardly, yet you could suffer from inner torment and anguish in various forms.
Sadly, the fact that there is so much political rivalry and other social conflict that seeks to evaluate enemies' mental health as a tactic for discrediting them means that you can't trust concern for your mental health as honest concern. How many people would like to assess Trump as mentally unhealthy in order to remove him from office? They don't care about his mental health, so what message does that send to all the other people in the world who might be suffering from mental health problems but fear talking about them because of the potential for abuse?
So mental health really isn't about outward behavior or social-attack, but because it is used this way it becomes practically a worthless consideration. The hate-culture has taken something that could have been used to make people feel happy and function well and has turned it into a weapon of hate to produce more fear and hate.