Just kind of makes me feel more unique, like character customisation in a game. I also have played a lot of economy based online games before, and idk why but it just seems so fun.
I didn't get into collectibles for a while after I joined the site. Then, one day I bought one collectible because it was a villager that I had in my town (Mint) and it all kind of snowballed from there. It can be really addicting once you get started. But I do love that it's another way, along with your avatar and signature, to customize your aesthetic on the site.
I didn't initially care about collectibles, seeing them as sort of neat to look at, but not something I could ever really get into. Back then, I'd rather have my TBT going toward unorderable items or villagers in Animal Crossing, or items or Pokémon themselves in Pokémon games.
As time went on and I started participating in forum events, I got sucked in. I was suddenly very interested. They're fun to earn if you participate in the events, and regardless of that, they're cute accessories that can add some flair to and accentuate your avatar and/or signature, or they could just simply look nice as a collection. They can also, as stated previously in the thread, showcase your interests. For just being little image boxes, they can be fairly versatile.
Now if only I had more TBT to spend, since not only am I in the market for collectibles, I do still have interest in purchasing in-game items.
I like making colour/theme coordinating aesthetic lineups. *insert Marge meme* I just think they're neat. Some have special meaning, like winning them in a contest, or some were even gifted. Some are also limited time things.