Everything went right for Luke in Star Wars. He learned the Force, joined the Rebellion, blew up the Death Star, and got a medal. Almost everything went wrong for him in The a Empire a Strikes Back. He got shot down in his snowspeeder, crashed his X-wing in a slimy mudhole, his friend got frozen in carbonate, got his hand cut off, and found out Vader is his father.

I think it will bet the same with Rey. She was large and in charge for TFA, but I bet she has some serious setbacks in store for TLJ. I think that tone contributes greatly to how popular TESB is.