I'm positive Joker has tried to kill himself though.
To think about the things he has, to see no point in existing, I imagine he would try to take his life, before finally dealing with it.
He has a disregard for life, because he has no regard for his own. Because he sees no point to it.
Existence to him is one big joke. People living by society's rules is one big joke. People living a normal life is frustrating for him.
Things he lost all sense in and it drove him mad.
He stepped into a void that he can't turn back from. Then he's trying to drag others into that void.
He wants to perform social experiments on people to break their spirits, like he has had his broken.
His belief is. If there was no authority or rules keeping restraints on us, molding us since birth to behave decent and good, then we'd be in a stage where we would cause chaos as monsters.
We wouldn't be monsters, would we? There would be no such thing as evil, because we would be exactly that without knowing what it even means.
Joker thinks, deep down, that people are inherently evil and it's because of society's rules and laws that keep us on the path of good.
He wants people to embrace the evil inside themselves, as that is who they truly are.
Madness is what opened his eyes to the truth about people.
Chaos is his master, because he knows, like I said, that it's the tool that will break the bonds that rules and law have molded us into being since birth, which is decent and good.
Within madness, comes chaos. It destroys existing establishment.
2 factors made him become, Joker.
A philosophical belief that existence is nothing but one big joke. Therefore, he doesn't feel the need to abide by laws and rules.
And the belief that human beings are twisted and evil deep down. Again, kept good, because of laws and rules.
Kept from seeing themselves for what they really are and the world that they live in. Their very existence, right down to the clothes they buy with money they earn slaving away in jobs, nothing but a joke, that they haven't realized in the way a certain someone has.
Combine those 2 things, and you've got the Joker. No wonder he went mad!