There are other things to consider.
Nobody is forced to pay the asking prices and if these prices are too high, items are less likely to sell.
Also, some folks do like to 'box swap' regularly as part of their enjoyment of what is after all, a hobby.
I think that profits are inevitable, but so are losses. I experience both on the modest amount of gear I move on.
Main system: MMs/ADCs/Low output MC's/One rare Japanese SUT/One scarce British phono stage/various tonearms/hefty Japanese DD TT and hefty Japanese BD TT and small British BD TT. 4 CD players/2 jitter buster/2 DACs/Valve buffer. TVC stepped attenuator or valve pre-amp or solid state pre-amp. Current dumping power-amp or either of two Class A SS power-amp or Class A EL34 valve monos or big Japanese (part Class A) integrated. Big dual concentric speakers/Smaller dual concentric speakers/Two way British compacts and full range speakers, amongst others. And too much more to list!