why do people feel the need to buy expensive cable

Well to each his own. I use clarity Cable interconnect and power cords  , atlas mavros speaker cables. One high fidelity power cord. Works fine for me to each his own. 

@calvinj whats the difference in the music when you compared the HFC to Clarity Cable interconnects and power cords?

High fidelity is more transparent quieter backgrounds and better prat. . Clarity has a more extended top end with a little bump in the upper midrange. Which my system needed a little of.  I like my cymbals to ride a little bit!

I have to say I am using Transparent Ultra Gen 5 cables with my new Focal Kanta No.2’s (Krell amplification and Yamaha CD S2100) ....just absolutely riveting!  So lifelike on all levels...shockingly realistic to the point of enveloping me in the acoustic and textures of the original event. Never have I heard audio reproduced so compelling and alive with every last ounce of low level details coupled with such a massive dynamic range and glorious harmonics.

and again, if you buy used, especially cables, you can often sell in a few years for no/little loss...

People almost never sell our cables. They keep them. Very rare on the used market. Everything else in the system goes, and repeatedly...but not the cables. There’s no where else to go...