But we also talk shit about the guy who exudes confidence and messes everything up. He actively makes stuff worse due to his attitude.

I'd rather own my mistakes than be a walking contradiction.

To be fair he's probably overconfident. But picking up any sense of false confidence(not a shy buddy attemping to 'fake it til you make it', more serious matters) is a massive red flag to me that I can't trust their judgement of their own knowledge or capabilities. Someone who says straight up it will be difficult gets a lot more trust from me.