why do people feel the need to buy expensive cable

I have much more expense in my ICs, PCs, and speaker wires then in my electronics. I have all High Fidelity Cables having gone from their initial CT-1 ($1600 for 1 m.) and up to their Pro ($18,900 for 1 m.). Yes, that is right, almost 12 times as much!! I also had an interconnect of their Elite series. It was better than the Pro, especial its bass, but enough is enough! And the Elite weighs 154 pounds in a 6 inch diameter and 37 inches long! Where would I put these?

So where did this investment in cables get me. I should say that other components including my amp, line stage, phono stage, dac, turntable, music server, and grounding unit, also greatly contributed to my sound. But my speakers are invisible and the speaker end of my room is replaced by a three dimensional sound stage with instruments with all harmonics and finger sounds playing them and singers who breath and turn their heads. And all of these have precise locations on stages.

My only regret is that I am 79 and only now have this music with its realism and thrill. 

Once in a great while I bother to read some of the drivel in the forums. I can truthfully say that I have never found anything useful here.
Willemj has a point. Years ago while I was at IIT in Chicago I majored briefly in Electrical Engineering. I did so only briefly as EE thought that knowing how to make a circuit that worked meant that further science to make a circuit that sounded better was irrelevant.

Shortly after that I went back to physics. EEs don't engage in science; they forsake it saying they know everything. I have a friend who is self taught and who has solved the problem of some frequencies getting through amplification faster than others. He has a focus control that makes everything else sound broken. I won't list his name as he will not bother with 1950s scientists.

Gdhal, "Untrue, to the extent there is any audible distinction a human can detect with the naked ear."

This is not true there is research to suggest that while our ears may not have responses noted in the brain of anything over 16k Hz, in noting the pleasure center of the brain on high fidelity recording when the highs above 16k are removed pleasure drops sharply.

Apparently there are other means by which the brain becomes aware.

But in reality no one is obligated to prove they hear differences in cables. You never are asked to prove that you don't hear a difference.

I might add that nobody ever asks why people buy expensive cars, wines, tvs, or steaks. What are you objective measures for these?

I don't give two hoots what you like.