why do people feel the need to buy expensive cable


I have tried expensive cables and one's moderately priced. I would say there were some differences but I can't actually say the expensive cables were better. IMHO I believe a lot of people buy expensive cables because they don't actual trust their ears and are afraid of making a mistake. They figure the expensive cables are better for the fact they cost more. If you have a difference of opinion or share the same thoughts, I would like to hear about it.
taters
It's always about system synergy starting with the room.

Wires come last once all the rest is tuned in.

If things are tackled in the right order biggest fish first then finding the right wires should not be nearly as hard.

If things are off to start with only so much to gain out of different wires. You could end up spending money on wires that would have been better served elsewhere before.
"He figures it cost 20 percent of retail to build a speaker. So for an example. If the Alexia retails for 52k than their cost should be around 10k. I would say that is a very big markup from manufacturing to retail."

He's just figuring. Only Wilson knows what it costs them to make a pair of speakers, and they're not going to tell anyone, including they're dealers. Product cost is the single most guarded secret in any business. If someone in a company that has access to that info tells you what they pay for something, they're lying. It could also be a scam like the auto industry and invoice pricing.
Garebear,

Just curious, what cables have you had for 20 years and what are you thinking about changing to?
Geoff - The word "expensive" is relative to the rest of the system, the speakers/amp/preamp/sources. $10k on cables is not expensive if the rest of the system is worth $100k. However if the rest of the system is worth $12k, then $10k on cables is very expensive and would most likely not be the most efficient money spent in terms of improved sound quality per dollar.

In my system, I think its expensive and inefficient to spend $5k total on cables, which is where I'd be if I spend $1k on a single set of interconnects. I can get more SQ improvement for the same money elsewhere. But that's of course for my system, thus the need to be open-minded about different levels of cables, results will vary for different people. I also have a dedicated power line for example, that might change things dramatically in terms of how cables respond.