I surmise that most audio cable naysayers cannot reconcile the cable's individual component costs with the final price. Looking from this angle I can see how high cable prices can rub folks the wrong way.
However, I don't consider the manufacturing costs/retail price, rather, I focus on price/performance.
For instance:
Option "A" use inexpensive cables
Option "B" try out a say $200 cable hopefully for free (borrow, returnable). Then I can decide if there is an uptick in performance, am I willing to pay $200 for this uptick? I can still not purchase and be no worse than option "A".
With option "B", at least I have choices and additional information (a data point) with zero $ invested and the possibility to elevate my system.
I suspect that many naysayers are not even willing to try, being emotionally resentful of the often steep pricing and entrenching their resentment with some argument.
I'm also of the belief that everything in the audio chain matters. Whether cables should be elevated to component level is subjective. For me, because I believe cables sound different from one another, I treat them as components. As I move up the audio food chain, I don't want my cables to be the weak bottleneck.
I agree that a lot of audio cable manufacture's advertisement/marketing is filled with a lot of subjective marketing hype, but I don't it reaches the level as being BS since BS can mean deceitful/lying.
When researching/shopping for components, I give the most weight to opinions of audiophiles who has purchased/used the component with no skin in the game (like a dealer peddling his product). If enough voices sing the same tune, I'm of the belief that I can obtain similar results if purchased - the caveat of course is it can be system dependent. I give little/no value to manufacturer's hype.
Is a person who purchases a expensive audio cable being duped by marketing hype, placebo, or false imagination? I'd say generally no, at least for the very expensive cables. Seems most are educated professionals (with incomes enough to further splurge in this high-end hobby) who when you read their reviews/posts, are very serious about the performance of their systems and are deliberate/thoughtful on why they purchased the cable and how it performs.
I don't believe that as the price of cables increase, their testimony validity decreases. If so, what's that based on?
Audio BS Facebook group? Taking a magnifying glass to outliers and calling it the truth is misleading. You need to get an "impartial" sample size(s) to be able to make educated guesses/claims regarding the population as a whole.