why do people feel the need to buy expensive cable

Two good points in the last two posts.
Those are the main problems in discussing the subtle audio changes audiophiles discuss.
Sadly both are used to accuse the 'other side' of being wrong...
I don't think there will ever be any agreement. Other than a possible we can agree to disagree.

Except, Elizabeth, the "subtle" (positive) changes that exotic cables may or may not be able to achieve, are reported as "jawdropping," dramatic," "night and day," etc.  If switching out a cable can make those kinds of improvements, you would have had to have been previously using metallic thread.

Additionally, cables shouldn't introduce anything into the music program, they should only eliminate outside interferences.  Anything else you "hear" after switching cables, IMO, is voodoo magic.

dynaquest4, 
I agree too often many use hyperbole to describe differences between cables. I've been guilty of it. I don't anymore,  but I do hear differences between cables. Do you think it's possible for a cable to lower the noise floor?

It’s oft times quite humorous and entertaining to read opinions about so called exotic cables that second guess what people who actually have experience with them say. What the ding dong? 

dynaquest4

... the "subtle" (positive) changes that exotic cables may or may not be able to achieve, are reported as "jawdropping," dramatic," "night and day," etc. If switching out a cable can make those kinds of improvements, you would have had to have been previously using metallic thread.

Not exactly. What you're describing are subjective impressions, so naturally they will vary from person to person. I've eaten burritos that I thought were much too hot, yet my wife thought they were just hot enough. Get it?