This is true, but like I said - ignoring anything but that toothless idea, you lose the ability to assess an item in the marketplace in terms collectors can appreciate (workmanship, comparisons to similar models, prestige of the brand, runaway conspicuous consumption..). For example, I just saw a thread on this forum about a series of Rolex Subs with the words "fυck 'em" printed on the dial selling for over $45,000. Now, people on that thread were quick to point out that whoever was willing to spend $45,000 on a fυck em' Rolex was an idiot and a tool - but when we're talking about spending $137,000 on a Speedmaster, well - let's call it at buyer's discretion. Talking rarity - there are technically less of those Rolex's than of the early Speedmasters.
There is a false equivalence here. Oxygen is the only stuff we can breath, but 2915's are not the only nice dive watches from the 1950's-1960's. Sure, there are less 2915's in the world every year as collectors and time take them from us - but the Speedmaster was not the only watch around. There are dozens of similar sports watch from that era, and made in similar or less numbers, that go for pathetically less than 2915's. Hell, very nice and rarer vintage Patek's can be had for less. Omega, Rolex, Patek - they all have a tax. A tax independent from the watch.
Still, I think we sort of agree.