Well, Since the population of the world is about 7.4 billion and a total of 9.2 million have been sold as of January 28th, 2016, It's over the amount you would need to have enough to have over 1000+ Followers on Miiverse or even 5000+. Plus, You can follow mulitiple Miiversers on one Mii and not just one ( Im pretty sure it's 1000 you can follow )