Risk assessment should be a rational and objective undertaking. As humans, with our emotions, can sometimes be irrational and subjective. As security professionals, this would seem to put us at odds with our duty to objectively assess, manage, and mitigate risk. Unfortunately, subjectivity introduces bias, which skews risk assessment. When too much subjectivity is mixed into risk assessment, it can produce a risk picture that is not an accurate representation of reality.
See: https://redskyal