Question: how come avatar is the highest grossing movie?
Answer: Avatar, released in December 2009, held the international box office record for almost a decade with $2,787,965,087 since 2010, having earned the top spot by passing Titanic's previous record of $1.9 billion after just 41 days in theaters. It took Avengers: Endgame a little over three months to beat Avatar's record.