I can see that to an extent but the market was crazy for these things, highs and lows within the same hour. It wasn’t like normal scratch hot items where it could take days for the market to spike. It just seems odd.
That can probably just be explained by speculators, tbh. It's an item people are gonna want basically forever (and it's an accessory so it'll be usable even with NGS bodies), so periodically a speculator will come in and buy a bunch, making the price swing higher to whatever their "no deal" point was, and then it'll start to go back down naturally until the next speculator comes along. It'll happen a minor amount with a lot of things, but with big ticket items like this it'll be a lot more noticeable, and this is probably the most iconic big ticket item I can really think of (aside from maybe wet towel or something).
I'd assume that the majority of those speculators will hold on to them until they leave rotation though to start offloading though when the price starts to rise, the OP really smells more like an exploit (whether it's duping or a stolen CC) to me. Buying for immediate resale only really works well if you can control the entire market + can buy up anyone who tries to undercut you (otherwise you're better just waiting to sell), and for something this expensive that's still in an active AC scratch that seems kind of unlikely. It makes more sense to me if these are items they got through nefarious means that they're just trying to offload ASAP via low prices.