According to "All time box office rank", Avengers: Endgame is 2019 holds the highest all-time gross at $2.7 billion. Box office gross is calculated by multiplying the number of tickets sold times the price of the ticket.

However, your great uncle said, "No, that's not true, when I was young, everyone went to see Star Wars back in 1977. I am sure that the original Star Wars movie sold more tickets than Avengers Endgame."

It turns out that your grandpa was right. Explain succinctly why. Do not include unnecessary information.