Optimism bias

Optimism bias is a cognitive bias that causes us to believe that they themselves are less likely to experience a negative event. Evidence, indicates that most people have ingrained optimism biases and that too much optimism is detrimental to mental health. The evolutionary psychology reasoning that it exists is that early humans had to risk their lives every day. If they were acting on pure rationality our line would have starved to death.

Death is the ultimate risk for humans. However, we need to do it, however if we thought about it too much we would not do anything. This is why medicine is so expensive in US and has to be socially administered in the majority of civilised countries. The greatest product you can see someone is the fear of death. The optimism bias has to exists otherwise nothing would be done.