why do people feel the need to buy expensive cable

Actually there are many things in Science that are not (rpt not) subject to revision. The absolute constant of the speed of light in a vacuum, the mass of an electron, all elements have exactly the same composition everywhere in the universe, the universe is expanding forever, the physical characteristics of a black hole have been known with absolute certainty since the 1960s, the hypotenuse of a right triangle given the other two sides is never in doubt, the equivalence of energy and mass (E= Mc2), all electromagnetic waves are comprised of photons, and all manufactured wire is directional. 

....... and all manufactured wire is directional.

Untrue, to the extent there is any audible distinction a human can detect with the naked ear.

The comments seem to  be  going a little off topic.
Please try to stay on topic for the best interest of the other members interested in the OP's Thread. 

I do not believe people feel the need to buy expensive cable, but if it sounds better and they can afford it, they buy it...not because of ads or salespeople but because they like the way it sounds...

Well, obviously if your hearing isn’t all it’s cracked up to be, you know, if you’re 105 years old or whatever, and/or your system is not (rpt not) revealing enough and/or has at least one or two errors in it and/or you don’t follow proper protocol for cable evaluation, such as using fully broken in cables, the chances are excellent you won’t hear much, if anything. If in fact any cable evaluation was actually performed which it probably wasn’t. Same as it always was, a lot of who shot John.