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.

Losing something we already have is twice as much pain than gaining the same. This skewed feelings towards loss is known as loss aversion.