“It takes over your mind. I don’t sleep. I train all day and  when I get home I often shadow box in my room.”

And that is the second part, the final secret to Conor’s confidence as well as his accurate predictions. True dedication.  

"I said it and it did it. I do talk but I do a whole lot more work"
Conor, like many great athletes is a living example of "hard work pays off".
He is confident, not because of his desire and vision alone, but his dedication. He knows that he spends more hours in the gym, works harder, won’t quit and doesn’t stop. Those are controllable variables and when you know you've done the most, that gives you confidence. Just like when you are having an argument with someone or somebody asks you a question. If you know the answer, because you've done the most research on that topic, you are confident in your answer. 

"Doubt is only removed by action. If you're not working, then that's where doubt comes in"
Even though Conor is talented and talent in my opinion does play a minor role, but more importantly he is obsessed with his vision, gives his all in the variables he can control (such as effort, speed and consistency), prepares to the highest level possible and right before a fight in the octagon, or ring tomorrow, knowing that he has done everything possible in his power to win the fight, which gives him a huge advantage and confidence while fighting and leaves no room for fear or doubt.

"It's a beautiful feeling when preparation meets opportunity. Nothing is impossible, you can achieve anything“