This is an analogy that is brought into discussions occasionally, so I am happy that Michael has brought it up.
"So to argue whether a wine or a lens is worth a certain price requires that one understand the background of the person making the argument. If they have the credentials, and make an observation or judgment on something within their field of expertise, then maybe one should listen-up. If they’re a neophyte with an opinion, and not much else, then maybe just nod, smile, and have another sip of wine."
This is certainly one side of the story. Someone who has dedicated large amount of time and resources on a subject might be expected to have more knowledge than the average person. There is, however, another side. Are anyone spending 4 or 12 hours a day on any subject automatically world-authorities on that subject? Throw in any controversial subject you like (homeopathy, global warming, etc).
Clearly, being very interested in something, living and breathing that subject and spending all of your money on something does not necessarily make your opinions "right". This is the reason that appeal to authority is a bad concept, authority so often have proven to be wrong. Good, thought-out arguments, supported by transparent chain of evidence and a convincing genuine interest in understanding the position of those participating in the discussion seems to be a much better path towards progress*). This is hard because it takes more time and more people-skills than simply calling people "neophytes" (I had to look that one up).
Interestingly, (at least some) sommeliers actually expose their supposed abilities to blind testing. While some fail, some seem to consistently be able to classify wines that I will never be able to do. This makes me respect their abilities and trade as something more substantial than snobbery, even though I (like Michael) may never be able to reach their levels personally.
Once a person (with some confidence) can reliably pick out (and prefer) the $200 wine from the $20 wine (or a $20000 camera from a $2000 one), the matter of if it is "worth it" is quite subjective and a matter of disposable income. Both are quite hard to argue. I do believe that the analogy has only limited value here, as reliable scientific (or science-inspired) tests for wine are reasonable to design, while similar tests for cameras are difficult and will typically only test one of several relevant aspects.
*)progress as in "humanity improving their collective understanding of a subject"