You obviously missed Adam Smith's pin factory analogy. Also there's something known as the economies of scale. High volume manufactures rely on standardization and repetitiveness to make their mass produced products economical for the consumers buying them. How many parts do you think that go into building a Honda Civic that aren't used on every other single product in Honda's line up? Almost none! The only thing that distinguishes one model from another is it's sheet metal and the way the individual parts are organized and configured.
Expensive European cars with the exception of certain "entry level" models are made to order in not very large numbers. Not to mention that most customers lease them and beat the snot out of them while they have them and once traded for a new one after 36 months or so the dealer's auction them off and you find them for sale at the Audubon Hoopty Ville on the Auto mile to ordinary people trying to look prestigious with upside-down financing with a lot of addons. The dealer's know full well that the commitment on the note will never be met (though they still make money) because the first time something breaks the car will come of the road and usually wind up in impound and if there is anything left to it, it will be auctioned again on the tuner market. Hence the 50% depreciation. On the other hand, buy a Honda, Toyota or Subaru, make your payments and take care of it, you actually have an investment!
Speakers may only have a few parts but R & D is expensive in any industry, you simply have to advance the state of the art at any price level to remain competitive and you know what? With the enormous diversity of new products available to hobbyists, with how their tastes change and the way they move products through their systems there is an equally enormous glut of very reliable used products for enthusiasts to choose from that keeps production volumes low and costs high. That's why you can easily pay thousands putting a basic, relatively speaking, system together.
Oh, no one pays 10% on a credit card or personal loan, how about 20%+ - 30%+!

