Watches, jewelry, and cars are something you display in public, stereos aren't. Conspicuous consumption and impressing people can be the name of the game for some. Who isn't impressed when a bright yellow Lamborghini drives up the street.
You can't sell a product unless you can make the buyer aware of the benefits and show how it is worth the money. For the average person with untrained ears, the audible improvements can be hard to perceive. Most people aren't going to sit in a dark room and listen to every single note being played and strain to hear the differences a $4,000 power cord makes.
Personal preference is another issue. If someone hears a $20,000 Thiel system they may hate that sound quality and think their clock radio sounds better. Maybe a $20,000 McIntosh would be worth the $20k.
Wilson has done a good job of marketing to create an aura of sophistication and highest quality. The sound quality is easy to pick up on. The Wilson sound has big bass and big dynamics. Neither comes cheap. Wilson leaves the "petty" little details to other designers i.e. run their Sophias on a Denon mini-system.
High End audio has done a lot to discredit themselves by supporting $400 wooden knobs, $5,000 speaker wire, $199 Clever Clocks. It's like a cult, once you're in you go for it, but will drive an outsider away and probably permanently bias them against the whole business permanently.