To start, Animal Crossing never really had merchandise until City Folk. Because that's around the time that the movie came out, if I recall. It was Japanese-only, but the characters in it got their own little toys and whatever because of that. Apollo, Brewster, Sable, etc. When New Leaf rolled around, Nintendo found a better face for AC merch: Isabelle. Because furries really, really wanted to fuck her. There still wasn't a lot, but Isabelle definitely was popular, so she started showing up on more things.
Then came the amiibo cards. it corresponded to the forgotten AC game: Happy Home Designer. You got these amiibo packs, hoped to get some good villagers which you used with some device and got the animal in the game to design their house. New Leaf then updated that if you had these amiibo cards, you could bring villagers into your towns. No longer did you have to rely on internet forums to get the highly wanted animals like Julian, Marshall, and .... Ankha.
Anyways, the packs weren't cheap but they weren't expensive either. But note, there was over 400 animals at this point. So there was a lot of cards to get. On eBay, the ugly villagers and undesirables went for pennies, while the high end ones went up to $100. Marshall in particular.
You could either play the gacha game by buying multiple packs or purchase him - and only him - on eBay. By this time in New Leaf's life, only the hardcore players were still around. The ones who actually made QR Codes, had perfect towns with Perfect Fruit trees, and did their dailies every day. So the amiibo cards were only really collectable to them.
Then came New Horizons. And, well. Yeah. AC became popular. I'd say 100 times more than New Leaf. And of course, with the popularity, Nintendo sees dollar signs.
And those amiibo cards? Exploded so much and scalped, Nintendo had to re-release them. Because hey, THEY deserve that money. You're supposed to spend hundreds on them to find your stupid squirrel boyfriend.
But yeah, here we are. You've probably see some of this stuff in those Gamer Girl Tiktoks. It's now a Wholesome UwU Brand to consoom. Get two Switches - an Animal Crossing one and then another to decorate with Console wraps. Get the controllers. Get the amiibos. Get fucking everything. Only the biggest AC fans would have all that shit, after all.
Not play the game long past when everyone loses interest.