why do people feel the need to buy expensive cable

I must say that I regretfully agree that everything matters. Last evening I listen to three ways to convert music in digital to analog on my music server. One was JRiver MC 20, another Signalyst, and the third Foobar. I was amazed that there were great differences in how about fifteen cuts sounded. Generally I find the Signalyst best but many cuts sounded better on Foobar and JRiver MC 20. Mostly these were 44.1 recordings but the quad native DSDs shined on Signalyst.

I am going no further in this quest of what sounds better. I will probably forgo using Foobar and with 44.1 will mainly use JRiver MC 21. On my many SACDs converted to DSD and new DSD recordings I will use Signalyst. There is no question that "bits are bits" is not true as all recordings passed being perfect. 

Believe me, I wish this were not true.

Most all of us agree cables are a critical part of a system but Calvin is right, you do not have to spend crazy money for cables - but you might have to spend crazy money to come to that conclusion.

Digital cables are where people are being had. $50 or so for a TOSLINK that provides good strain relief and kink resistance, DONE.

It's a process. I think you have to be patient. I also think you are the judge of what your system needs.  Find something that's good.  Find a match and live with it.  I think those who have more income are able to try the higher priced stuff.  I'm glad that I have been able to own some of the high fidelity products as well as listen to Rick's system.  I also listened to the late Dave baskin's system. Both systems were uber expensive but they sounded great.  However they were polar opposites and sounded nothing alike.  We have to appreciate the music and what your system does and enjoy it all.  Not obsess over it.  

This makes for interesting reading:

https://en.wikipedia.org/wiki/Speaker_wire