why do people feel the need to buy expensive cable

Price means next to nothing, I look at it in categories because one companies mid range may cost more than another company's extreme product, and the cheaper one may blow that away because their extreme costs over $20,000.

So how about this more pertinent approach?
entry
mid range
high end performer
ultra ridiculous, but appropriate for certain systems

Many companies that make a great range of the three haven't managed to create an ultra cable, and some of those are out into 40 and 50 grand.

Transparent, MIT, Nordost, Audioquest, Kimber, all make mid ranges from $1500 to a few thousand dollars, while there are companies making their top cable that blows them away for under $1000.

...and had nothing of value to say, nothing. Much like half of the other responses.

So what if you took a cable apart and think it is made from wire you can get at a hardware store? Not all cable companies are doing that, many create their own alloys, they use exotic versions of oxygen free copper, they try annealing and baking in ovens at different temperatures and times, many are cryo treating cables. They are experimenting on systems that are obviously allowing them to hear what guys with DIY wire will NEVER, ever hear in their systems.

So what if you "listened" to an expensive cable and couldn't hear any difference.

When someone has a question about expensive cable, those who can't hear the difference have nothing to add to the conversation that should mean anything to the person who has the questions.

Who should you "trust" or "believe", the audiophiles who have figured out how to get a system that is detailed enough to hear the differences in any cables, interconnects, or power cords, or the nimrods that can't hear the difference between anything?

Notice a common denominator among those who think it's ludicrous to spend any serious money on cable? They all have DIY cable and stock power cords.