[Overconfidence, ][1] may fit the context you describe:

• the overconfidence effect is a well-established bias in which a person's subjective confidence in his or her judgments is reliably greater than the objective accuracy of those judgments, especially when confidence is relatively high.

 
• For example, in some quizzes, people rate their answers as "99% certain" but are wrong 40% of the time.

Or excessive [self-confidence][2]:

• The socio-psychological concept of self-confidence relates to self-assurance in one's personal judgment, ability, power, etc.

(from Wikipedia) [1]: http://en.m.wikipedia.org/wiki/Overconfidence_effect [2]: http://en.m.wikipedia.org/wiki/Self-confidence

Overconfidence, may fit the context you describe:

• the overconfidence effect is a well-established bias in which a person's subjective confidence in his or her judgments is reliably greater than the objective accuracy of those judgments, especially when confidence is relatively high.

• For example, in some quizzes, people rate their answers as "99% certain" but are wrong 40% of the time.

Or excessive self-confidence:

• The socio-psychological concept of self-confidence relates to self-assurance in one's personal judgment, ability, power, etc.

(from Wikipedia)