Yeah, my understanding is that the recommendation engine was already developed for a news app popular in India, and that they grafted this onto Musical.ly (the acquisition which has now become TikTok).
Also, they spent many, many millions on ads to get the app everywhere.
many, many millions can be approximately equal to 1bn. I am aware that they advertised a lot, but didn't have (and wouldn't trust) any figures provided on this, as I've seen how wrong they can be.
Also, they spent many, many millions on ads to get the app everywhere.