ByteDance's growth hack that got them tens of millions of users:

working with distributors to pre-install their flagship news app Toutiao in mid-tier Android phones at $0.06 per install 

qDAU or not is another question but interesting case study.

(started reading this book during my flight)

wow, that's a crazy strategy! pre-installing apps is such a smart move, especially for reaching a huge audience quickly. it's like sneaky but genius at the same time. definitely makes me wanna read more about ByteDance and their tactics. thanks for sharing, i might just have to check out that book too!