Optimism Bias:

Optimism bias, also called positivity bias or unrealistic optimism, is a cognitive bias that overestimates likelihood of positive outcomes and underestimates negative events as likely to have bad outcomes. Optimum bias helps give us hope and motivation, encouraging us to take risks and pursue goals, despite challenges. Overreliance can lead to poor decision-making, being unprepared for potential problems, and disappointed when negative events occur. Research suggests adults focus more on their own risk factors than those of others, leading to a biased perception of risk. The optimism bias may have evolved as a survival mechanism, helping individuals to persevere through difficult times and maintain a positive outlook. Also see Illusion of Control.