why do people feel the need to buy expensive cable

The resolution capabilities of your system will directly impact the impact (good or bad) of the cables in your audio emjoymemt.
That elusive ethereal positive impact us an alchemy derived from the synergy (or lack of it) from ALL of ICs, speaker and power cables, layered on to the synergy with your electronics and your speakers.

High Price -- in isolation to the above -- is a red herring other than quality build product costs .... Full stop.

One size does not fit all - I've heard high end cables that sound great in system A but swapped into system B, they sounded like sh*t.

"Compelled to buy " ...... Hardly.

"Elective to do so".... Absolutely, if

(A) you have the quality build kit with the resolution capabilities to make it work and --ergo-- make it worthwhile.

(B) Here's a litmus test reported by a third party attending reporter who was reporting on the shared observations of the thousands of attendees at the TAVES audio expo in Toronto in Nov 2014.

NORDOST ran its demonstration symposiums and the following is the reporters review in Canadahifi mag.

With reference to (A) above , his conclusions summarize it well

Nordost

"...
I had a chance to sit in on a couple demonstrations in the Nordost room, giving my feet a well deserved break. I’m very familiar with the benefits of high quality cables and use a full Nordost Heimdall 2 loom with my reference two-channel setup. That being said, I always find the Nordost demonstrations to be an “ear-opening” experience. Michael Taylor from Nordost demonstrated the significant sonic benefits of replacing an OEM cable with a Nordost model – in particular 1) a swap of a single USB cable, from OEM to Nordost Blue Heaven ($250/2m), to Heimdall 2 ($500/2m) and; 2) a swap of a single RCA interconnect, from OEM, to Blue Heaven, to Heimdall 2, to Tyr 2 and finally Valhalla 2. Along with convincing the audience in the room that cables DO matter, I’ve now got the bug to upgrade...."

zephyr24069. 1,141 posts. 12-03-2017 8:34am

"...There seems to be a downturn/trend on Audiogon over the last couple of years and this thread and others like it which are indicative of the moving away from people helping each other to the best of their ability to a forum where people like to stir the pot, criticize others and hide behind their moniker...."

+1..... Nailed it!! The quoted prior post characterization above of the OP is the hallmark and embodiment of an internet troll post.

Internet "troll" per Wikipedia:

"....In Internet slang, a troll (/troʊl, trɒl/) is a person who sows discord on the Internet by starting quarrels or upsetting people, by posting inflammatory, extraneous, or off-topic messages in an online community (such as a newsgroup, forum, chat room, or blog) with the intent of provoking readers into an emotional response or of otherwise disrupting normal, on-topic discussion, often for the troll’s amusement...."

To the Forum Moderators

12 pages in: .... don’t feed the troll. Please Kill this thread .

bigamp
Q: why do people feel the need to keep asking questions like the OP? Does it make them feel better?

A: see Wikipedia

In Internet slang, a troll is a person who sows discord on the Internet by starting quarrels or upsetting people, by posting inflammatory, extraneous, or off-topic messages in an online community (such as a newsgroup, forum, chat room, or blog) with the intent of provoking readers into an emotional response or of otherwise disrupting normal, on-topic discussion, often for the troll's amusement...