Great comment, Zane. Your comments just about sum me up as a collector. I am that collector that gets bored of watches after a year and is on to another grail, another company, another complication. I do not have the income to acquire 100 individual high-end watches nor the patience to save-up. I see something I really want and like a child that obsesses over that one toy, I start selling specific watches in my current collection in order to afford that new "grail."
For me there are two levels of "grail." one level of "grail" is a watch that I want, can financially conceive of owning today and it becomes my new obsession for acquisition. the other level of "grail" is that conventional theory of a watch that is so financially out of your reaches that you may never be able to afford it; assuming you can find it!! ex. a Jean-Claude Killy 6236 with full box/papers in mint condition.
anyway back to the topic, my perception of dealer v. collector focuses on whether the person is selling for a profit in order to financially support themselves; possibly as their sole profession. i believe this excludes a collector who has THEN fallen on tough financial times and needs to sell his collection for survival. considering the minute differences between watches, i believe a collector can also be a dealer. i mean how else could you stand to differentiate between Mark I v. Mark 3 dials!?!? but the truth of the matter is the person is selling for profit, in order to survive and pay rent/mortgage/etc.
i think for many dealers here that have long established relationships as trustworthy dealers, their words on the forum can be seen as sources of guidance and knowledge. due to their profession, they may have handled many versions of a watch that us collectors have ONLY read about it. so we "need" their knowledge and experiences to guide our own knowledge. i think we can all admit that there some aspects of a watch that just cannot be photographed. I think that is why so many of us purchase watches from a few top-end dealers. as opposed to some bait-and-switch double talk dealer that seeks to get the buyer's money at a super premium. its trust and an expectation that we are getting EXACTLY what we are paying for and nothing else.