That was the gist of Alan Moore's 'The Killing Joke,' that one man exposed to a series of devastating personal experiences would go mad.
More accurately, in
Killing Joke it was the Joker's proposition that
anyone exposed to a series of devastating personal experiences would go mad, that the entire world is just "one bad day" away from being the Joker. Crucially, what
Killing Joke has and this movie
appears not to have is the counterpoint of Jim Gordon, who disproves the Joker's contention by not going mad.
I'm never going to argue that
KJ is a good book, but I'd suggest basing a movie on it and stripping out that rather crucial element leaves you with the proposition that the modern world is horrible, violent and senseless and that madness and reciprocal violence are an understandable response to it.
I don't think that's helpful.