Joker is not just a movie, it is a character study about a mentally unstable man who had delusional thoughts and was sad at every moment in a city which was going through tough times and people were angry with the privileged class. We can't say that society created the Joker, it just triggered an unstable man.
Other things about the movie might spoil it but It is surely a masterpiece with brilliant acting performances and plot. You will love it for sure.
And don't think that it justifies violence, No it doesn't. The Joker was feeling happy after killing those who he didn't like. He had no political or any other ideas to kill someone.
A 10/10, 100/100 movie it is❤❤