Avatar's extended theatrical rerelease only netted some thirty million dollars worldwide — a drop in the bucket of its billions. It's Titanic that really benefited to the tune of nearly $350M upon 3D rerelease in 2012. Avatar had the advantage of inflated 3D ticket prices from the start, and benefited tremendously from convincing everyone to shell out the extra cash.

It's true that China loved Avatar — it ended its run with a gross 3x as high as the next highest-grossing film — but this was 2009/10, when the Chinese box office was smaller, so that was "only" about $200M. (For context, it made $760M in the US & Canada.) If you took away China and the rerelease, Avatar would still be the highest-grossing film of all time with plenty of room to spare. It was that big.