Buyers do 'exist', adverts seem to get a handful of views (even without PRICE DROP clickbait titles - might help a little though).
And at least some of them have buying power, so that's not an issue.
There is just no commitment, even if they initiate a conversation.
(Which is sometimes a bit ironic, if you feel that they might have made a wrong call there. But even as a buyer, I can act like that.)
They are either newbies looking at everything, open to buying anything used or new.
Or old-timers, who are Veeery specific about what they want (and at what prices, obviously).
So, why it sits for so long. if there is interest?
The way I see it (from successful sales) is: It has to be Just in the "right window", where they Just sold something (after some time...) or Just got that thing that happens to work well with My thing (so they think, and on some occasions, you see it relisted, thinking: "Why on earth? I actually really liked that thing, he was happy, too..."), etc.
High-end audio is fairly tricky. There is stuff I've been constantly looking to try for years. I wish there wasn't, give it a few decades (hopefully years), that little list may be ticked off. Or rather it will be me burning out, feeling like "I've had enough of new excitement, not fun anymore" for the most part, and a simple "Retirement" sounds a lot better.

But usually, it is a case of "it just wasn't to be" mainly, because of bank account limits, probably all the better for it.
Trade would be really fun, wouldn't mind trying a bit of that. But in reality, making those complicated deals is hardly feasible without meeting in person, where parties don't need to worry about whether doing a good thing or not. It's not quick, and it's not easy.
Most of my sales to the US, even being EU-based, if I was restricted to that, it would be more difficult, those products might be less common there, hence a little demand.
One thing facebook marketplace and other sites have is not only showing you views (periodically), but there is also a Watchlist, which is a bit more useful, as it gives you at least some indication of actual interest, and it may change if you drop the price etc.
Lots of spam though, and feedback system is absolutely garbage. I only have one negative for like a stupid 50$ item the buyer wanted to unfairly negotiate down in person and nothing else - and the only way to have it removed would be to make a new profile.
Completely unfair, while others are simply unable to leave me anything positive, since the option never comes up.
I don't understand why they just removed all old feedback instead of just putting some warnings on it or whatever... - but at least there is still a working system.
So yes. The option is there to sell it quicker, with substantially reduced prices and/or more eBay fees, etc. otherwise it is a simple practice of trying to make a decent ad and then be patient, helpful, unforceful, etc. all the right things.