Because you like Ron Woodruff in Dallas Buyers Club

Brilliant, violent, and only a little insane, the Joker doesn't listen to anyone except the voices in his head. See them in DC Extended Universe.

Some say to survive in Underland you need to be as mad as a hatter–which, luckily, he is. See them in Alice in Wonderland.

With great power comes great responsibility, but Peter Parker always seems to get the short end of that bargain. See them in Marvel Cinematic Universe.