How is this one of the highest grossing movies of all time?

Rating: 4/10 (26 December 2018)

Doctor Zhivago is impressive in scale. . .and that's about it. This film features remarkable sets, a variety of locations and plenty of extras, but the plot is incomprehensible and there is a lack of chemistry between the actors. Plus, they play the same sappy music for the entire 197-minute run time. How on earth is this one of the highest grossing movies of all time (adjusted for inflation)?