A few days ago, I collected my 7,000th badge in the free-to-use Nintendo Badge Arcade on 3DS.
Previously, I documented what happens when 5,000 and 6,000 badges are earned. The Arcade Bunny actually reveals a secret code word. Not sure what it is used for but perhaps it can be used a sequel..? Also, I got all these badges without spending a single cent as I milk the free plays each day.
When 7,000 badges are collected, the Arcade Bunny presents the player with a dialog option. See the video here for more.
With the 3DS eShop closing soon, it is assumed that the Badge Arcade will go down with it. So if you want badges, better get them now before it is too late.