[flipp3r]

One of the reasons is probably that people are using Pokemon Go in countries where it hasn't been released yet. For example here in The Netherlands there's 1.3 million+ players, even though the game is not even available yet in the Android or iOS app stores in The Netherlands.

[chatmasta]

I'm currently traveling in Hungary and was able to download the game on the first day of release. Is that because my Apple account has a US billing address?

[flipp3r]

I use Android myself but I've heard from colleagues that if you use a US account you can download it here. For Android it's just downloading executable through any channel that isn't Google's play store.