You don't merely need a lot of data, you need the right kind of data: if e.g. You have lots of users but only a few transactions per user to base your predictio

You don't merely need a lot of data, you need the right kind of data: if e.g. You have lots of users but only a few transactions per user to base your predictions on you won't get very far. There are a lot more likes in facebook's system than transactions in netflix's