Joker was incredibly stereotypical in its portrayal of mentally ill/psychotic people though. Fiction affects reality and portraying the joker, a violent and abusive murderer, as psychotic doesn't help with the stigmas against real life psychotic people (i am one of them) because it just reinforces the misconceptions that we are dangerous.
We are never given Arthur's diagnoses, so I can only assume he suffers from a range of illnesses, that share comorbidity. He shows symptoms from a range of disorders/illnesses, such as PTSD (which Joaquin has discussed during many interviews), depression, anxiety, possible restrictive eating disorder, as well as various personality disorders (Antisocial personality disorder and borderline personality disorder, both share the common symptom of uncontrolable anger, amongst others). He is experiencing various levels of psychosis throughout the film (hallucinations, delusions, and a high sense of grandeur), and due to a sudden stop in medication, he relapses into experiencing those symptoms at an extreme. Whilst he is in major withdrawal (it mentions he is on 7 different medications) he also loses his job, his mother suffers a stroke, he's being mocked on television (or so he might think (perhaps a delusion that Murray is out to get him! Perhaps a symbol of the collective society that dismisses him!)) and he's aware of all the negativity in the world. Here we have two very extreme triggers, environmental triggers and chemical triggers, and so it becomes more likely that he may suffer from uncontrolable anger. He is angry that he is in such a powerless position in the world. He discovers that he was abused as a child and neglected by his adoptive mother. The anger and confusion of all of this happening at once could lead to an extreme case of someone experiencing psychosis, as well as many other disorders, harming themselves or others. This is an extreme case. This film is a dramatic interpretation of a fictional villain (who has many origin stories) who presents himself as a clown, who's main enemy is a man who dresses as a bat. And one could even argue that the murders, guest appearence, and inspired revolution are all dellusions and hallucinations. He could be completely out of touch with reality. He could just be taking responsability so he has visability, which is all he really wants.
Educated people are going to understand this and not fear those who have psychosis. Hopefully they will teach the less educated.
Saying all of this, the film industry has some work to do with portraying mental illness without ignorance, without the extreme scenario, without the very uncommon possibility of criminal ability. I'm not denying that.
I think it's a high posibility that the majority of the audience will be able to empathise with Arthur/Joker, and not necesarily blame his mental illness on his *possible* actions, for we see hundreds, maybe thousands rioting in clown masks. Are they all mentally ill? To the extreme extent as Arthur? No and No. I can now argue that the film could be saying that it's the environmental and societal issues that lead to the actions that the rioters take in Joker, and not untreated mental illness. (Meaning the real, working class, people are pissed at the government, the rich in power, for being greedy af so they're creating an uprising.) Joker is but one member of this vast amount of the general public. People are rioting against the tyranny they feel they're living in. It's political.
If it weren't for the status of the Joker, as a well known villain and character, world wide, the film-makers could have chosen any member of the rioters and told their story of why they seek power (because they feel utterly powerless in a world that neglects the poor, and the minorities). All they've done is call the dude Joker and claimed it's the about the guy from the Detective Comics.
