why do people feel the need to buy expensive cable


I have tried expensive cables and one's moderately priced. I would say there were some differences but I can't actually say the expensive cables were better. IMHO I believe a lot of people buy expensive cables because they don't actual trust their ears and are afraid of making a mistake. They figure the expensive cables are better for the fact they cost more. If you have a difference of opinion or share the same thoughts, I would like to hear about it.
taters
So I disconnected all of my power cords and replaced them with the stock cords. I didn't tell my wife what I did, but asked her to listen to a couple of her favorite songs. Her reaction, what happened to the bass, his voice sounds dead, it doesn't sound good,  what did you do? Hearing improvements makes one a believer. 
Once in a great while I bother to read some of the drivel in the forums. I can truthfully say that I have never found anything useful here.
Willemj has a point. Years ago while I was at IIT in Chicago I majored briefly in Electrical Engineering. I did so only briefly as EE thought that knowing how to make a circuit that worked meant that further science to make a circuit that sounded better was irrelevant.

Shortly after that I went back to physics. EEs don't engage in science; they forsake it saying they know everything. I have a friend who is self taught and who has solved the problem of some frequencies getting through amplification faster than others. He has a focus control that makes everything else sound broken. I won't list his name as he will not bother with 1950s scientists.
I think this guy gets it right:

"[Nature] ... never says "Yes" to a theory. In the most favorable cases it says "Maybe," and in the great majority of cases simply "No." If an experiment agrees with a theory it means for the latter "Maybe," and if it does not agree it means "No." Probably every theory will someday experience its "No"—most theories, soon after conception."

                                                       Albert Einstein

The quote is in an article in Forbes titled "Scientific Proof Is a Myth". The main premise of the article is that "nothing in science can ever truly be proven. It's always subject to revision."

https://www.forbes.com/sites/startswithabang/2017/11/22/scientific-proof-is-a-myth/#78d5fbb62fb1

Interesting article that is pertinent to the cable debate, IMO.

OK, boys and girls, what time is it? It’s time for a little, What the heck is happening to science these days? Taken from Zen and the Art of Debunkery. Enjoy. Italics provided by your humble scribe.

Seeing with humility, curiosity and fresh eyes was once the main point of science. But today it is often a different story. As the scientific enterprise has been bent toward exploitation, institutionalization, hyperspecialization and new orthodoxy, it has increasingly preoccupied itself with disconnected facts in a psychological, social and ecological vacuum. So disconnected has official science become from the greater scheme of things, that it tends to deny or disregard entire domains of reality and to satisfy itself with reducing all of life and consciousness to a dead physics.

As the millennium turns, science seems in many ways to be treading the weary path of the religions it presumed to replace. Where free, dispassionate inquiry once reigned, emotions now run high in the defense of a fundamentalized "scientific truth." As anomalies mount up beneath a sea of denial, defenders of the Faith and the Kingdom cling with increasing self-righteousness to the hull of a sinking paradigm. Faced with provocative evidence of things undreamt of in their philosophy, many otherwise mature scientists revert to a kind of skeptical infantilism characterized by blind faith in the absoluteness of the familiar. Small wonder, then, that so many promising fields of inquiry remain shrouded in superstition, ignorance, denial, disinformation, taboo . . . and debunkery.
"[Nature] ... never says "Yes" to a theory. In the most favorable cases it says "Maybe," and in the great majority of cases simply "No." If an experiment agrees with a theory it means for the latter "Maybe," and if it does not agree it means "No." Probably every theory will someday experience its "No"—most theories, soon after conception."

Albert Einstein


>>>>As fate would have it in this hobby when a test proves negative it actually doesn’t mean “No.” It means “Maybe” because maybe the test was flawed and we’ll have to have someone else take a crack at it. And if the results are positive it probably means YES to the theory, though prudence dictates we get some more postive results on board for good measure. Any test is only one data point. Apologies to Albert.