How can someone really be an internet expert?

Had a great lunch today with a fellow SEO (search engine optimizer)- and it got me thinking, how can anyone ever really be an "internet guru?" If I am ever away from the internet for an afternoon, I feel like I know absolutely nothing. No really, NOTHING.

In this job, there are always new things to learn, new techniques, new sites, new measurement features ... it never ends! How can anyone really be an expert?

Just because something worked well for one client doesn't mean it may translate to your next. The shelf life of anything online is comparable to those greasy noodles from a Chinese restaurant. When you leave it out on a napkin overnight, it disintegrates into it's own goo. (Try it! Now imagine what it's doing to your body.)

I would be afraid of an SEO that touts they can guarantee placement, and says they are the greatest SEO out there. Confidence is a wonderful thing, but when your job is to keep your clients as relevant as possible, check your ego at the door and let the teacher be the student.