With all due respect, anyone who would claim that about themselves is not only arrogant, but also not very smart. I read your entire post and I'll believe you when you say that have a quick grasp at technical theory, but the very fact that you point out that it still takes practice and learning to master skills completely denounces that claim "you know everything". It does take learning, it does take practice and it does trying and failing multiple times times to perfect any skill or discipline. There is no master of any craft that would claim to know everything. Even if one has learned all there is to know about something, doesn't mean there isn't something new to discover. Smart people in that position are not satisfied by "knowing everything", they push the boundaries to discover something new and better. That's how science, engineering, medicine, civilisation itself advances. If humans believed we "knew everything", we'd all still be living in caves hitting animals with sticks so we could eat.
You can't know everything, that's ridiculous. All you've really proven by saying that is how much you actually have left to learn.