Would you believe that the average person expects to live a better-than-average life? The math doesn't add up, but this skewed perception is quite common.
Optimism bias, also known as positivity bias, is the tendency for people to overestimate their probability of experiencing positive events and underestimate the likelihood of experiencing adverse events.
For instance, a person may believe they have an outsized chance to live longer, be wildly successful in their career, or win the lottery due to optimism bias.
The illusion that things will always go smoothly can also cause you to significantly underestimate how long it will take you to get things done. The Nobel Prize-winning author of Thinking, Fast and Slow, Daniel Kahneman, calls this problem the planning fallacy.