From my buyer's perspective, sharing one factor in the sale FWIW: I
valued the clear provenance extremely highly, probably higher than most. Given the high cost of 1 BTC nowadays, I personally require a very strong lineage before even considering making an offer.
That mattered to me more than the fact that it's ungraded and not the most perfect specimen -- though I still look for a certain minimum quality, and I also highly valued that the coin was
handled and
stored very carefully for all of these years.
OP
showed where the coin was
bought from, which the original owner
vouched for; the original owner is a long-time member who
sourced the coin directly from Mike Caldwell. And we have records from 10 years ago showing all of this, with the timelines matching when the coin was produced (one of the final batches ever produced). So all of that was important in my purchasing decision.
Finally, I wanted to finally secure a coin relatively quickly after starting a halfhearted attempt three years ago. The silver gilts seem relatively rare nowadays, with a nice one only appearing once every few months on these forums, so I didn't want to wait a few more months/years for another good coin to show up.
Different buyers will have different factors they value, but those were mine.