I think certainly directing is a visual medium, but it's also about communication, and a lot of times great directors are lacking in communication skills, which is rather shocking to discover that.
I feel like I'm the best actor on the planet and I also feel like I'm a fraud. I think hubris comes from insecurity. Confidence comes in a more rooted sense; part of being confident is being able to say, "I can be really shitty," and to accept that. But also not to crumble under it.