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
It is a little bit pessimistic picture. I try to stay optimistic.

Pessimist:  It is so bad it cannot be any worse
Optimist:    Yes, it can!  Yes, it can!
Inequality is indeed on the increase everywhere, and that is not good news for the mass of the population or for growth prospects. 

Even if you have
Even if you need
I don't mean to stare
We don't have to breed
We could plant a house
We could build a tree
I don't even care
We could have all three
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.