You sure? VGC is telling me it sold 5.61m
And that would include double dipping on the remaster too, something that Uncharted 3 didn't have, so it's really not comparable. I can't see it selling 10m+ It wouldn't surprise me if it didn't even do 5m.
I included God of War Saga sales (which is God of War 1/2/3).
But I didn't realize there was a second God of War 3 Remastered SKU on PS4 (that one with 0.02M). This would put it at 6.50M.