the reason...for the same reason most of us buy or want to buy expensive components. The desire is to obtain great sound. I spent on equipment at first and only thought about cables afterward, having been exposed to the idea that good cables made a significant difference, by reading about it here, for the most part.
I will add that it is easier to spend a couple of hundred on a cable than coming up with the money needed to buy better components, thus there is appeal in that sense. The OPs "expensive" is still undefined, if it is thousands then I have no idea why some people do it. Perhaps they have spent much, much more on their equipment and this the final tweak.
I did find that certain cables made a meaningful difference in sound quality and others did not. The price didn't seem to be the defining factor.
But I have not spent thousands on individual cables, so my experience is limited by my cheapness, about $500 and mostly less. Most normal, non audiophiles would consider that much spent on wires to be truly insane.
I will add that it is easier to spend a couple of hundred on a cable than coming up with the money needed to buy better components, thus there is appeal in that sense. The OPs "expensive" is still undefined, if it is thousands then I have no idea why some people do it. Perhaps they have spent much, much more on their equipment and this the final tweak.
I did find that certain cables made a meaningful difference in sound quality and others did not. The price didn't seem to be the defining factor.
But I have not spent thousands on individual cables, so my experience is limited by my cheapness, about $500 and mostly less. Most normal, non audiophiles would consider that much spent on wires to be truly insane.