I had a thought, which I'm finding difficult to complete. It goes something like this.
My partner's father is not very good with computers. I don't think he really gets them, so he often will ask my partner for help with the computer. Now, my partner's no whiz-kid with computers, so whenever she has a crazy problem she'll ask me to fix it. I'm pretty good with computers - I work with them all day every day. However, when I can't answer something, I'll ask Chris about how to fix my problem. I'm not sure who he goes to for answers - the next step up the chain would have to be someone like Linux Torvalds, and I don't think they know each other.
What's my point, you're asking? It's that to someone else, you may be a computer genius. But then I got to thinking about it, and it's really not just related to computers. You could do it with any particular subject.
So, on the grand scheme of things, you may be an expert compared to someone else.