What makes a DAC so expensive?

If you can listen and distinguish clearly these 5 brass instruments intermingled with one another in a totally gleaming space, encompassing your room and exceeding the speakers in all direction even the extreme left and extreme right... Your system is good...

Empire brass ensemble "Gabrieli"

https://www.youtube.com/watch?v=olIrf-uioD8

If you can listen to this piano music of Chopin, Nocturnes by Ivan Moravec, and if the piano is in front of you low chord at your right, higher chords at your left, and completey out of the speakers....
Your system is good...

https://www.youtube.com/watch?v=5BaLVjoLUAQ

The last one is difficult to have it right...

This is my favorite therapeutic music... Very powerful...Goldman "Holy Harmony"

But you must listen very subtle chimes on top of very precise pulsating tuning forks frequencies encompassing the room and in front of you a Mantra by superposed female and male voices...

https://www.youtube.com/watch?v=aJRpoUk-mpU&t=344s

Try to buy the cd if you like them on youtube....

Mahgister,

Always been a big Groucho fan. You’re quotes reminded me to do some binging on old "You Bet Your Life" episodes available on Tubi.

Still waiting for some of those deep philosophical quotes, but the quick wit is on full display,

 Not one of my attributed citation comes from Groucho.... He is more swift and humorous than i ever will be and i borrow his reputation to navigate with my own  philosophical rambling flaws....

:)

What makes a DAC so expensive:

Audiophiles who think that the more expensive a product is, the better it must be....

The complexity of the build ,the power supplies, are essential in the S/N  and purity of signal, many aftermarket linear power supplies are over $1500 alone ,brand name , how fancy the case 
If a R2R multi ladder dac each resistor has be matched to possibly hundreds of resistors ,clock ovens all kinds of add o to empty your wallet DCS dacs with all maxed out power supplies ,and super clocks $90k combo, the best sounding digital on the planet 
that can rival the best of Anything out there, but Slightly out of my budget !!

Those that don’t want to spend the money justify having not done so.

Those that have spent the money justify having done so. 
And so the wheel turns, and turns, and turns. To me it comes down to what camp your ears tell you your in. 
I went from a Bluesound Node 2i to a separate Audio Mirror DAC followed by replacing the Node completely with the addition of a LUMIN Streamer. Both phases of the transition were substantial but heavily weighted towards adding the separate DAC. No comparison.