I think you could rather say, is all HiFi overpriced? My answer would be yes. Having said that, DACs may be one area where there are bargains or relative bargains. Companies like Mytek,, Metrum, Rega. Chord, and others, make some great kit at reasonable prices.
Looking at HiFi from a business perspective, the problem seems to be about scale. The golden age for Hifi, the 60's to 80's say, then every home aspired to a good HiFi system, now only a small %. If you are spending money on R&D, tooling production facilities and you only sell a few 100 or 1000 units, it is going to be expensive.