I daresay that vintage owners/sellers have sat on instruments for a very long time and the earth has shifted beneath their feet.
1) I used to attend an annual show. The same exhibitors every year, the same guitars, the same prices. It was obviously their belief that price elasticity of demand did not exist. Most of them were older/retirees. They merely packed up, moved to the next show and set up the tables and chairs again hoping for a sucker.
2) The prevailing attitude was that they were going to wait until someone paid over the odds and make a nice little $10-15k score.
3) They also seemed to say - or said outright - that if they couldn't sell the instrument at their price they would pass it on to their children. But children these days aren't playing as much guitar. And they often have no idea about or interest in its worth. They might sell for $8-10k or what the market will bear but they are iPhone/DAW/MIDI/synth musicians and aren't all that fussed about year of make or model or features etc. So the grand 'heirloom' plan isn't necessarily working out. Amps are an even more difficult sale due to the bulk, size, weight, care & feeding of old tube builds and the fact that modelers and other tech are available to guitarists of any age, skill, genre, intended use etc.
4) As Father Time taps them ever more firmly on the shoulder with each passing day, what will they do?
5) The debate about relics will never end peacefully but the reality is that a) relics and vintage instruments are damned hard to tell apart in many cases b) many high-end/custom shop guitars, especially Fender clones, are relic'd c) a high-end guitar (relic or otherwise) and a vintage instrument are very close in spec, quality, playability....and price. But not always. If the high-end relic reissue is $2k less than a vintage of even questionable provenance then the vintage guitar/owner may frequently lose out.
6) One analogy might be classic cars especially at classic car shows. The hot rodder still in the game at age 60 is now seeking to exit the game and fast now that he's got a bad hip or bad back and can no longer work on his car at age 80 - not to mention the scarcity and cost of parts. He may have sold his house and moved/downsized (no garage or storage). Or he has medical expenses. We played a gig at a massive car show and I was somewhat surprised at the number of vehicles for sale. Perhaps it's similar to a guitar show where a 'sale' is actually just a feeler but many of the window stickers indicated the sellers were quite motivated to find a buyer - not least because hauling a car around is even more burdensome than the heaviest Fender Twin.