I think it is "5."
As you haven't consider the biggest cost involved in creating OF-like platform with 1.25 million DAU. It is, without a shadow of doubt, the marketing cost.
That line item in the cost sheet is the trickiest to quantify.
Because there is a first mover advantage involved. If you can identify a valid niche, it costs very little. People just come to you because there is no where else to go. Like starting a forest fire in summers.
But if you are the second app that is trying to be the new OF, or the 10,000th marketing agency trying get clients, your cost will hell lot more.