There are 4 factors at play that make top-end audio gear very expensive.
1. Some fixed costs are higher in absolute terms, e.g. more extensive R&D to get the voicing right and achieve the desired balance of musical virtues... the last 10% of tweaking can take an infinite amount of time.
2. Fixed costs are spread out over a production run measured in the tens or hundreds.... as opposed to hundreds of thousands for mass market gear
2. Some variable costs are higher, e.g. high end capacitors vs generic stuff; more complex circuit designs may require more parts; small production runs may require manual assembly rather than machines
4. And, in some cases, because some people equate price with quality and some manufacturers find that they can afford to be less diligent while still charge more.
A high end manufacturer make several hundred or thousand dollars from selling a single item, but how many items to do they sell? I'd like to know about their total profits or, as a proxy, their lifestyle. I expect many are comfortable, but not extravagant, and that many are struggling.
I am not implying that all high end gear represents fair prices. Some items provide much better value than others. The burden is on us to listen and decide for ourselves. Don't get caught up in hype.