Are interconnect cables worth $15,000?

A friend was demonstrating his new multi thousand buck cables to me recently ( i think they were nordost)I wasnt really paying much attention to the brand since I roll my own. His old cables were sitting nearby. When he left the room for awhile I switched the cables. He returned and we continued to listen for several hours. He never noticed and I never mentioned it. To this day he has never said anything about it. I cant wait to switch his new power cord out for the one from my old dell if I get the chance.

In another "meanie of the month" episode at a recording studio I spend a lot of time in. We have westlake bbsm10's driven by brystons with either 2"tape source or digital through apogees sent through the summing buss of a vintage restored neve console. The speakers are connected with the fattest cables Ive ever seen that came from westlake and were very expensive. As the owner claimed the cables made a big difference I suggested we try some old monster cable I had and give a listen. 5 people were there that day and the only one who heard a definate improvement with the westlake cables was the owner. I suggested he was delusional, he asserts we are deaf. In the end its in the ear (or imagination) of the beholder. And really since he paid for the cables Im quite happy to listen through them.