LinkAlso rockstar apologizes for the troubles in GTA V servers because of the massive population!Link
Yeah they never really had the servers to take the whole load. Which is rather odd considering they had the sells figure before the Online Release date.
That's because initial server outages like this are engineered.
It makes it look in more demand, and therefore better in the minds of most consumers, than they predicted.
The idea is that "yeah it sold a billion dollars in a few hours, but LOOK AT HOW MUCH MORE IN DEMAND IT IS!"
It's standard marketing.
Like when a retail store stocks only a small number of a new product, so they can sell out quickly, and then say how popular it is.