why do people feel the need to buy expensive cable

For those who want more information, from well known electronics engineer Douglas Self: http://www.douglas-self.com/ampins/pseudo/subjectv.htm
With quite a bit of bibliography for those keen to enlarge their knowledge.

I’m always in awe of anyone who knows the limits of my perception. Gosh, does that Mr. Self dude have like, ESP or something? I’m guessing a little but here but Mr. Self isn’t on board the Tweak Train, is he? 🚂 Toot, toot!

Don't drive Elizabeth away!  Hers is one of the all-too-few voices of reason and moderation on this forum.

So far ZERO people have ’changed sides’, which I agree with. But I do think the discussion (or argument) has its merits. People who are new to the better audio world, and are not set in their ways, may find the information helpful, but also confusing. Hopefully, this will lead them to trust their ears and not someone else in the buying decision.

Mr Self does not need ESP. He has a first class honours degree in engineering from Cambridge University (i.e the top 10% of his year) and then psychoacoustics at Sussex University. For years he worked with audio legend Peter Baxandall and a number of well known electronics manufacturers. He holds a number of patents on electronics design and is the author of a classic book on amplifier design. Geoff I cannot help it if you have never heard of him.
This is what he wrote on the directionality of cables: "Cables are directional, and pass audio better in one direction than the other."
Audio signals are AC. Cables cannot be directional any more than 2 + 2 can equal 5. Anyone prepared to believe this nonsense won't be capable of designing amplifiers, so there seems no point in further comment.