I think I've discovered a psychological condition.
Nessun Dorma Syndrome, or NDS for short: the state-of-mind on realising the gaping chasm between singing a popular aria from an opera and the ability to sing the entire role from that opera in an opera house. Also known as the Habanera Delusion and the Brindisi Complex.
The patient may, with plastic surgery and lots of eye make-up, learn to live in the state of delusion or simply be too dim to see the inherent problem as a problem at all. In this case it helps if the patient cannot actually sing the popular aria itself, except possibly in a much lower key, and thinks of the words of the aria as a sort of nonsensical shopping list in a funny foreign language. In time the patient will give up any intention of singing the entire role and may possibly marry a daytime TV presenter. In this case NDS can, hopefully, be safely contained within a very small area of Wales.
In some cases, amongst those with enough awareness of the inherent problem, NDS can manifest itself in an outburst of rejection: the patient, on realising his (or her) possible shortcomings, spurns the entire medium of opera rather than face his (or her) dilemma head on. "If I dump it, it can't dump me" is the essence of what is happening, and the patient never faces the danger of revealing his (or her) shortcomings to a more discerning audience. The general public then believes the problem to be with the medium rather than with the NDS sufferer himself (or herself). In this way the patient can live with the condition, eventually convincing himself (or herself) that he (or she) never actually had NDS but rather that he (or she) was never given the opportunity by the opera establishment to prove what he (or she) could really do.