I disagree with Diego. I truly do believe Conor thinks he is the best in the world. The human ego can be absolutely astonishingly boundless, especially when talking about elite professionals. For the sake of self preservation, motivation and the ability to move forward, the ego convinces the individual that it is different, it is better, it is right and never wrong, etc... I cannot imagine being a professional fighter and thinking, 'yeah, I am just average. I will probably get humiliated in there'.
Most people, for the sake of being less abrasive, tend to say things that will not insult other people or place themselves above/apart from other people. This is why Ali, Conor and Chael have been so fascinating, they are just giving us a buffet of stream of conscious thought, saying things that aren't socially acceptable, things that are inaccurate to us but nonetheless, things that they really feel are true.
Much of this ego checking process has to do with growing up, fear/anxiety, repetitive failures but I definitely feel that Conor, as well as almost nearly every other elite fighter, feels that they are the best. Heck, there was a time when I was in 3rd grade that I thought I may have been the fastest kid in the world. Then, in 4th grade I got beat in a race and started to realize how ridiculous my mind was acting, just because I never tasted defeat. This growing process that takes place after defeat is the reason I have been so fascinated by the likes of Conor, Jones, Silva and all professionals that are incredibly confident but due to the nature of life, will in time fail and be forced to reevaluate.