As I’ve stated before when this has come up, she’s looking for for her place in the world. At first she thinks she’s looking for someone to show her her purpose, by the end of TLJ she’s coming to understand that she’ll find her purpose on her own. Everything she does comes down to that and her innate goodness (which are connected, she longs for connection and is isolated but empathetic - look at her saving BB8, empathetic to his plight and ultimately finds kinship with him). Even without building the new Jedi she has still found the place she was looking for with her friends in the Resistance. She hasn’t been forced into anything except situations, where it was up to her to make active choices about where she wants to take her life path.