Why so many Berkeley DACs for sale right now?

When shopping for DACs recently, I noticed that the Berkeley flagship DAC was praised to the skies by reviewers. So I went on Audiogon to see if there might be a used one for sale (seemed unlikely at the time, given the DAC's reputation). Imagine my surprise when I saw three people currently trying to get rid of what some consider to be the best DAC available. And now today I noticed a fourth. I know that there is an upgrade that just came out, but apparently owners of earlier versions can get the upgrade for a fraction of the cost of a new unit. Anyone know what's going on? 
Nothing unusual here, some folks like to have the latest version. As soon as the newer version announced, they try to dump the older version. Even with the upgrade path, the ‘upgraded’ version has no advantage in resale value, not to mention the 2-4 months wait time before they start accepting old DAC’s for upgrades.

What I don’t understand is the company’s design and marketing philosophy....the 3rd "reference" version in 4 years? And still no true DSD or USB support? If you want to use USB, you have to buy one of their not so inexpensive converter box. For DSD files playback, you have to convert the signal to PCM via 3rd party software like JRiver Media Center.

At $22k, these are major negatives for anyone considering to buy a SOTA digital to analog converter.
Thanks for the response. Interesting: "Even with the upgrade path, the ‘upgraded’ version has no advantage in resale value." Is that true? I would think an upgraded version would have higher resale value. Shows you how much I know about these things.
Having had some long drawn out conversations about some tech considerations (brainstorming), with one of the people at Berkeley, a number of years back:

I can say with strong confidence that Berkeley will very likely not issue a product with even a smidgen of compromise in the area of sound quality. If it is a step backward in that area, for the sake of convenience, or any sake at all, it simply did not happen. They would not do it.

If a feature is missing then there is strong likelihood that they found the path of getting there was a sonic downgrade. Quality over compromise -any level of compromise.

Then the other thing of some folks being gear flippers, flippers so far gone..that they cannot recognize the best they’ll ever hear ---- when they hear it. They’ve lost their center - or they never had it. The game is no longer the beauty of music, or never was.