I definetly agree with one statement: The more you learn, the more you realize how little you know!
I'd say the measure of an expert is the amount of time spent researching, learning, and gaining in depth understanding of the chemistry and the animals. How long someone has kept fish doesn't necessarily mean a thing. Working at PetCo I spoke with a number of people who claimed to have kept fish their whole lives, yet were unfamiliar with what a "nitrogen cycle" is....yikes.