Final answer:
The patient is displaying grandiosity, which is a symptom of bipolar disorder where individuals have an inflated sense of self-importance, believing that they possess extraordinary talents or abilities.
Step-by-step explanation:
The patient is displaying grandiosity. Grandiosity is a symptom of bipolar disorder where individuals have an inflated sense of self-importance, believing that they possess extraordinary talents or abilities. In this case, the patient believes that their tenor voice is superior to those of the famous three tenors.