Star Wars' production problems prompted Lucas to visit his pal Spielberg on the set of Close Encounters of the Third Kind. Both men argued that the other's film would perform better at the box office, leading to an unusual wager.
“He said, ‘Oh my God, your movie is going to be so much more successful than Star Wars! This is gonna be the biggest hit of all time. I can’t believe this set. I can’t believe what you’re getting, and oh my goodness,'" Spielberg said of Lucas. "He said, ‘All right, I’ll tell you what. I’ll trade some points with you. You want to trade some points? I’ll give you 2.5 percent of Star Wars if you give me 2.5 percent of Close Encounters. So I said, ‘Sure, I’ll gamble with that. Great.’”
Both films came out in 1977. Though Close Encounters made an impressive $303 million, it didn't even come close to Star Wars worldwide gross of $775 million that year.
According to Business Insider, 2.5 percent of Star Wars' success -- when adjusted for inflation -- amounts to $40 million and counting in profit for Spielberg.