It comes down to the price difference rather than the percentage difference and thats where it gets tricky.
A $500 cable is twice the price of a $250... and the difference is $250...so you can "absorb" that mentally to some degree.
A $50,000 turntable is twice the price of a $25,000 but the difference is $25,000.. it gets harder to understand what engineering differences (and therefore musicality) $25,000 gets you.
A $100,000 speaker is s twice the price of a $50,000 but the difference is $50,000.. it gets harder again to understand what engineering differences (and therefore musicality) $50,000 gets you.
So for me its not the cost of the product, it is what in absolute terms these massive price differences gain you.
And the very interesting thing is most of us can name 90% of the car manufactures that produce high priced cars.... but in the world of audio every new audio show has some new set of manufacturers hawking a statement product. That indicates that there is a lot of "phising" going on at the high end of the high end, trying to part people from their money.
I remember I think it was at the last RMAF that Boulder produced a new statement power amp... the case work was HUGH... as was the price... and the explanation for the hugh case work was that buyers in Asia like their amps to be physically imposing.. so it had zip to do with sound quality... and all to do with marketing.
So thats also the issue with high priced gear... at what point does the tech side get left behind and the "jewelry" aspect take over?
Again... for me its to do with skepticism... and if I did have the money... I would still want to know that the dollars I paid out actually got me a meaningful benefit.
Peter