Neglect Of Probability
Neglect of probability is a cognitive bias that causes a person to disregard probability when unsure about a decision. It is a way in which people violate the typical "normative" rules for decision making (i.e. weighing the positives against the negatives and then choosing the most positive solution). In this type of decision-making, risks (when dealing with simple decisions) tend to be either ignored or blown out of proportion.
An example of this could be an athlete in training that attempts to perform a feat that is beyond their level of training, ignoring the possibility of severe accident or injury.