The Pessimist vs the Optimist

Some would argue that being a pessimist is the better of the two options, first of all because if you think about the worst happening, you are either right or pleasantly suprised. Secondly the pessimist would argue that they are always right and generally thats because everything is bad.
What I don't understand is, most pessimists I know claim to be right all the time, if you are a true pessimist and expecting the worst wouldn't you always believe you were going to be wrong, and if you were wrong about the worst, does that mean something good would happen?
Then you have the optimist. Some people claim that they are blind to reality, always expecting the best out of everyone and every situation. Some would argue that that the optimist is either wrong or not so pleasantly supised. But it seems that no matter how wrong the optimist, there is something within them that makes being wrong of no consequence.
So maybe the issue is not of being half empty or half full but whether or not being right matters to you. The pessimist is "always" right and the optimist doesnt seem to take into account that being right or wrong matters. Outside of our own pride does it matter if we are right?
Bad things are bound to happen, but so are good things. I dont know, I like being around happy people.