Hi-end audio has ***ALWAYS*** been a lousy market. It has never sold well. It's never going to get any better either as the lower priced gear continues to improve and the higher priced stuff today is really all about demonstrating to people that yours is bigger than theirs.
Certain products will hold their value and the savvy buyer will know what they are. Used gear is already depreciated, so it is much more likely to hold value.
Today's $6000 wonder DAC is tomorrow's $3000 white elephant.