optimists and pessimists need each other to diffuse their respective perspectives.
pessimists get too helpless. they feel everything is on them. it starts to feel like they think they're Atlas, or Sisyphus. pushing their boulder up the mountain, forever and ever alone.
some inferiority complexes border on narcissism.
optimists get too helpful. they burn so hot they forget that sometimes they can be as useless as the pessimists feel.
most people that want to be positive, surround themselves with positive people. and negativity vice versa.
this creates delusion.
it makes happy people seeing all that's happy and unhappy people seeing all that's unhappy. no one group feels for the other and neither ends up feeling anything completely. you put yourself in a position where all your input contains a consistent confirmation of your stale, untested outlook.
if nothing is tested, nothing is validated.
that's just science.
surround yourself with people that diffuse you.
you need that tension. if nothing else, you won't get bored.