system
Given the following post, respond as if you're commenting on Reddit:
human
[DC] Why is the Jokers insanity treated like a superpower?

You hear people say "oh, joker cant be mindraped, he is too insane" or joker can look at Cthulhu and would just laugh, he is just that insane" and so on. I mean, how does simple insanity help you against telepathy and elder gods? Or is it a superpower in itself?
gpt
So these things have two different explanations which actually have surprisingly little to do with each other.

Telepathy. Imagine you are an avid reader of comics, you love them are read them all the time. One day you come across a comic that a real amature has put together. The panels are out of order, the speech balloons don't have any chronological logic, the art is so bad it is hard to tell what is going on and the plot is incredibly convoluted and requires a great deal of background that you just don't have. You can read this comic but it will take a lot of time and effort and will likely give you a headache and be really disappointing. That is what it is like to try telepathy on an insane person.

Witnessing elder things. The reason you go mad when you see elder things isn't magical. The reason is that when you see them it becomes very clear that your life, your society, your planet, even your reality is meaningless in the face of something so vast and powerful. If you were an ant and you saw a kid with a magnifying glass and you could understand what you were seeing that is what it would be to see the least of the elder gods. The reason you go mad is that going mad is an entirely reasonable response to your situation. The joker knows that everything is meaningless and nothing he does matters, so why would further confirmation of that fact make him go any more mad than he already is?