The tendency to over-expect the probability of good things happening while negating the likelihood of anything bad happening is a common human trait.

Both optimism and pessimism are judgemental biases that try to bend reality inside our minds and can lead to worse outcomes and suboptimal levels of happiness.

To make good decisions, one has to have accurate, reliable information, free from any bias or prejudice.

Pessimism, or having a bias towards a negative outcome, has a fan base too, as it seems that pessimists are immune to disappointment.