I would expect many of the best-selling books of all time to be about journeys, but can I prove it? I checked out the list of Wikipedia and the Goodreads list on which it’s based. I decided to be strict and only include books in which the journey is absolutely central. So for example, I left out The Little Prince though he travels from his planet to Earth because he spends most of the story at one location in the desert, and Watership Down because the rabbits’ journey of re-location only takes up the first part of the book
2/13 dabbled with (I’ve seen the film of The Life of Pi and read part of Don Quixote)
1/13 never heard of before now. That would be The Celestine Prophecy.
On the other hand, I have read 30/100 of the best-selling books of all time, a higher than average score. The credit must go to my child to whom I’ve read most of the dozen or so picture books in the list!