Obviously more R&D than you and I care to fully understand. In your honest opinion do you really believe all these cable companies are running a massive scam? I think you should think about what you write. If you’re not interested or cannot hear a difference that’s fine. But you don’t have the right to say anybody who does hear a difference is stupid. What qualifies you to make these statements. I can pass a comment on any product developed with the same ignorance but I know that there is so much more that we need to learn and discover.
First of all, I haven't called anyone stupid. Ignorance is simply not knowing, and simply gathering up verified facts and making an effort to understand how things work will cure that. Stupidity is not being willing to make that effort and refusing to understand when someone who knows more about the subject explains it. You are listening and gathering facts and attempting to understand, aren't you? I'm not going to ask you to just take my word for it. I'm going to point you to the facts so you can read and understand for yourself.
Assuming you are, the conductive properties of different metals are known. And a simple measurement will tell you what the differences are. The limits of human hearing have been studied and are understood as well and measurements are a good indicator of what is audible and what isn't. A cable either transmits a signal accurately from one end of it to the other, or it doesn't. A cable can't improve a signal, it can only degrade it by improper manufacture or design. Let's talk about interconnects... it is VERY simple to create an interconnect that transparently conducts a line level audio signal from one end to the other. A two dollar interconnect can do that just as well as a $900 one. I'd refer you to the first post in this thread that has ample proof of that...
https://www.head-fi.org/threads/testing-audiophile-claims-and-myths.486598/
OK. Have you read that? So there's proof that all properly functioning cables sound the same. Why would anyone want to buy an expensive one? Maybe they pull and plug in their cables a lot and they want a stronger connector and reinforced cable skin. Maybe they have a lot of EMI and need extra shielding. Maybe they just like the look of cloth covering on their cables. These are all valid reasons to spend a little bit more... but sound quality isn't one of those reasons.
Why would a manufacturer want to make people think that their cable is better manufactured and performs better in some way than their competitors' cables? Well, that should be obvious. They want to convince you to buy their product, no someone else's. But if their product made a significant audible improvement, they wouldn't rely on sales pitch, they would show you the results of solid controlled listening tests proving that their product sounds better. They can't do that, so they publish pseudo-technical gobbledegook like the stuff quoted above, and they let their customers (who don't have any responsibility as a seller for the veracity of what they say) to make outlandish claims based on subjective impressions colored by bias and perceptual error.
Cable design has been pretty much the same for over a century. There aren't any patents preventing companies from using superior technology. And it costs very little to make a good cable. Companies in China do it in large quantities for pocket change. The reason that the audiophile press and retailers focus on fancy cables is because the mark up on them is astronomical. They may have to discount the amp you're buying to be competitive with Amazon, but if they can convince you to drop $100 or more on a cable to go with it, they've made a nice tidy profit on the sale.
None of this is illegal. It's just business. The old saying goes, "Caveat emptor." (Let the buyer beware.) It's up to you to make informed purchases if you want to get your money's worth. If you don't care about spending more than you need to, just go out and buy whatever is the most expensive. But don't fool yourself into believing that it sounds better because it cost more.
If you truly do want to cure your ignorance, I'd suggest you spend an afternoon going over the first post in this thread. There's a lot of info there that can help you make smart purchases, not stupid ones.
https://www.head-fi.org/threads/testing-audiophile-claims-and-myths.486598/