Keep in mind that you're comparing an outlier low price on a used camera (at least in the US, going rate for a used GFX 100 in good condition is closer to $3k) to MSRP on a brand new camera that many people purchase as much as a lifestyle/fashion item as they do for any other reason. Most of the people who buy an X100 VI would be better off just spending the money on the latest iPhone Pro if they don't already have it. It'll look just as good for most of their use case, give them an integrated wide angle and telephoto option, and it can use apps to post directly to their social media platforms of choice. 😅
I can also say that after years of travel and trying to fit the GFX 100 into various smaller camera bags, the size of the GFX 100 II was a major selling point for me.