I think one can't say to himself he is brilliant, this is so dangerous.
My father tells me how much surprised it is when he sees back their school mates,now that he is retired, they expected the brilliant people in class to success.
This is what really happened:
The brilliant people(3 hipersmart guys) took a normal job and lived a normal live. People that had enormous problems in school, became presidents of big companies, made their own restaurants chains,got political power, became famous as scientific researchers...
Wow: Nobody would have expected that!!
I think those brilliant people were very good at learning and memorizing when the answer is known, but not so good facing risk and failure, fighting against unknown.
PS: There was a time I got 10 over 10 score in some exams like math when a lot of people didn't pass. I felt great(and superior) about being considered intelligent, but at the same I felt frightened about losing my position, so I stooped asking stupid questions (what would they think about me).
Later I discovered I love asking stupid questions, and I love testing new things, often it goes bad, so I felt liberated making enough grades and not being ultrasmart, but feeling this stupid man can kick some smart asses if I work hard.