I don't actually think that's true. I think a Pessimist is someone who always assumes everything will go wrong.
I assume things will be fine... and then... they always go wrong.
At the very least, that's an Optimistic-Pessimist, right?
The Optimist says: "Hey, I finally drew a comic! Yeah!"
The Optimistic-Pessimist is saying: "Hello? Can anyone hear me? There must be someone who can help!?"
The Pessimist: "I'm cracking. These aren't the Cracks-That-Let-In-The-Light. These are the ones where parts of you fall off."