Late to the party here. JMHO-A $50K DAC would most likely be surrounded with similar priced electronics, cables, speakers and a room with treatments. Therefor it is very likely that the sound quality would be more easily distinguished. So for that person it will be likely worth it to them.
Is it possible to find a good DAC for under $50, 000?
Apparently, the good folks at The Absolute Sound have you covered.
https://www.youtube.com/watch?v=nItR8Z6CCWE
(Audiophiles are never going to shed their out of touch reputation with journalism like this. I'm sorry, but it's just so tone deaf.)