Many movies attempt to portray the challenges that mental illness brings, but few hit the nail on the head the way Joker does.
Arthur is just a man trying his best to live by abiding by societal standards. The political system betrays him, and he is forced down a path that was inevitable for someone as sick as himself.
So many of us can't put ourselves in others' shoes because we're so obsessed with ourselves that we can't be bothered to wonder how someone else interprets society. Joker perfectly depicts what happens when the mentally ill are treated like they can help their own condition and should just act like everyone else, not grasping just how impossible that can be for some