Quoted from glasairpilot:Everyone hated BM66 until the full code came out. Premiums were selling as low as $6500 for catwoman editions. Now $10k won’t buy you one
More like a case of 'buyers remorse' and the idea of inventory tipping the balance. The games were not being dumped. The game code really pivoted in 2017 and in 2018 the code was flushed out. Catwoman games were done in the summer of 2019 as a re-run. Whenever a game is re-ran it temporarily impacts prices as the dump of new inventory impacts availability. By 2019 we are in the market where people buy the hype on everything... so tons of people buy catwoman... and in turn tons of people end up dumping catwoman because they weren't really into the title in the first place or were trying to be flippers and flopped.
BM66 basically got a 'vault'/blackarrow edition (catwoman) that took a title from 'harder to find' to having a temporary glut of NIB games available.. which lobbed off the top of the price ladder as the game was readily available. The game had already gone from 'bones' to a fully flushed out 'war and peace' starting back in 2017 and into 2018. Which is probably a good reason why they did the re-run before wrapping it up in 2019.
Now, 2+ years latter the inventory situation has settled back down again and prices increase as the game isn't readily available in NIB form.
TLDR - Reruns always lob off the top of the price escalation as the abundance of NIB-level games negates scarcity. It takes awhile for that to settle again.
AC/DC is another example whose price escalation got neutered by the reruns because of the glut of virtually new condition games that were floating around.