Labubus got extra kick from being gambling also. Many were sold in boxes without labels or with minimal labels that listed possible contents. That makes the actual product into more of a loot box kind of thing. That might have contributed to the speed of the trend passing.
I think I heard it was a bit more than that - you'd buy them online direct, blind, and be informed immediately after purchase what it was you'd actually bought, so bringing in the immediacy and "convenience" of online gambling/gacha/etc. too, compared to ordering a mystery box and opening it when it was delivered, or buying foil packs of trading cards where you need to actually be present at a particular location.
"Gatcha", from Japanese "gatchapon"; there's little dispenser machines which sell plastic eggs containing a random collectible from a set. There are thousands of different product lines.
Basically game lootboxes, but IRL. People like gambling, it seems.
Protip: If you call it an investment, it becomes not only respectable but it is in fact the responsible thing to do for your customer's financial security.
Pogs, Tazos, Pokémon cards (all cards actually), Happy Meals, Knuckleheads/Gogos were/are still all sold lootbox style.
I think a Labubu novelty was lots of direct sales and a deliberately(?) flaky website that had people frantically strategising for secret methods to get an order placed successfully. When you did, they told you what you got without having to wait for it to arrive for an instant dopamine payout.
I suspect if the website worked very predicably and you could easily and calmly reserve what you wanted, even with the gacha mechanism, it would not have been such a frenzy.
