why do people feel the need to buy expensive cable

Don't "phool" yourself.  People buy watches, cars, homes, furniture, clothes, audio speakers...hell, even pets for the looks and what it says about their financial status.  I get that.  Just don't try to slide by me that you buy $22,000.00 speaker wire for the audio performance.

Some expensive cables do provide better performance for commensurate gear.  At some point there is diminishing returns for sure.  My experience is that most of the cable companies sell plain old wire dressed up in diamonds and pearls.  There are only 2 major companies that offer actual technology and real world improvement for audio signals and they are Transparent and MIT.  MIT makes some phenomenal stuff across a broad range of pricing, as does Transparent.  Many other brands offer good stuff, but their performance does not go up as the price increases.

There are more than two companies that offer real world improvement and technology. Come on Dave B. Clarity Cable guy was a nasa engineer. Other cables offer improvement real world when properly matched. 

True, although performance doesn’t necessarily track as their price increases.  Fundamentally, I also have experienced far less differences in cable designs that basically just try to dress up the wires with some sort of pseudo techno babble that results in marginal performance changes.  For my money and to my ears, those manufacturers who actually do something that essentially addresses the real world problems faced by an audio signal produce drastically better results.

Not even good old honest techno babble.