why do people feel the need to buy expensive cable

You have to see what a system can do first and that's down to the details. Placement, the room, speaker stands, cabling, power. All these things can sometimes make a system sound ten times better than it did because they were overlooked.

Of those things mentioned by pokee1016, cables are least likely to make an improvement is audio quality...assuming good quality (proper length and resistance) cables are already being used.  Basic, good quality cables are not expensive.

I agree that most cables are of a similar design and can be had fairly inexpensively.  However, Transparent and MIT cables are demonstrably superior at creating a lifelike reproduction of the music.  They offer a broad range of products for both the audiophile on a budget to the no holds barred crowd!   Choices are great these days, solutions abound for all types of audio enthusiasts...enjoy and stop arguing over which is thee best for everyone.  

 
dave_b
(I agree that) most cables are of a similar design and can be had fairly inexpensively.

That’s a patently false statement. There are solid core cables, there are stranded core cable. There are cables that have hollow conductors. There are cables with multiple solid core conductors. There are cables with air dielectric, cables with Teflon dielectric, cables with polypropylene dielectric. There are cables as thin as a human hair. There are 10 ga cables. There are silver cables, copper cables, liquid cables, carbon cables, graphene cables, cryod cables. There are cables that use single crystal copper. There are cables that use ultra pure copper. There are cables that use some gold mixed in with the silver. There are shielded and unshielded cables. There are cables that are controlled for directionality and cables that aren’t. Some cables have carbon fiber sleeves.