Not everything sold at full price. By six month, it was probably closer to 50M. GTA Online has a much higher cost basis. It is not a magic trick to generate free cash. Again, they need to NET $2 billion, not gross $2 billion.
Again, GTA6 really has to match the success of GTA5 or else it will lose money. You don't know if it can.
That's grossing $2 billion. But they'll still lose money at that point. They will have to net $2 billion, which won't happen until they sell like $4 billion or more.
It will be the most expensive game in history, with a reputed development budget of around $2 billion. Anyone can do the math and realize that it would have to sell in ridiculous numbers to make that up. If it doesn't capture the magic of past GTA releases, it will be a massive money loser.