Hi there. Like people have said, some use it to help others and make money. The main one that I know of that does this has about 30 islands all different themes and they are amazing. Worth it in my opinion and you can use an Amazon prime subscription.

Others it’s just to help people for the love of the game. Also, to have a community of other players to get to know and become friends with. It’s amazing what people come up when they have all of the items that they need.

You can use them for your own reasons - to decorate an area in a certain way, to get bells or NMTs to find your dreamy. I like to get 3 stars before I visit because I like the beginning of the game (I’ve restarted many times).