why do people feel the need to buy expensive cable

I must admit I have been a bit obtuse, but in all seriousness, happiness can be had all over the place with cables depending on your expectations and experience level. Of course the level of your system being critical. As for me, having had more gear and cables than a person has a right to, I have come to rely on MIT for one reason....they make listening to music more thrilling and lifelike. That being said, I once had a mid level system hooked up with Monster M series cables that sounded utterly fantastic.

I'm hoping for some "Trickle Down Economics" on this topic as well.

Cables are luxury and convenience.
Mega priced ones beautifully designed for looks, but experimenting with sound differences is truly sufficient few bucks instead of $30,000. All I did when I was child is to connect solid core wire or stranded picked up from the electronic lab where I was learning. I wasn't sure how much it was worth(perhaps half-dollar per meter), but I heard differences especially if solid core wire was used.
I can bet lots to find same wire that will sound same or better than $30,000 cable.
They made only for ones that don't know the difference between $3 and $30,000. Many would agree

Map, if that happens write down all the details for it will the first time in human history !

One can hope...