It would be easy to find data to show that 99.99% of people aren't the best tennis player or fastest runner or best Scrabble player in the world; therefore, nobody can be the best at it. According to this reasoning, at least.
And when I say rational basis, that's its own challenge. There is a huge potential for emotional thinking disguised as rational and for self-delusion. Everyone wants to believe they are the top 0.01%, and most of them are wrong.