I don't really think a beginner does realize how much they don't know. Really I don't think any of us really understand how much there is to this craft. I know I don't. It is just amazing; that is what is so fascinating about it I think.
I've told this story before, but it bares repeating. Years ago I was knitting along, sitting in the living room of the lady who owned the little LYS in my town that was right in her home. I considered her a great knitting (crocheting too) guru (still do) and I asked her, "So Verla, how long did it take you to learn everything about knitting?". Without missing a beat she answered, "I don't know everything about knitting". Right then was when I began to get a hint of how much I didn't know. If Verla didn't know everything, I was sure I never would.