Yeah, that's why Bruce Willis tells you you shouldn't care about the time travel.
Time travel here is an instrument used to explore questions of nurture, destination, agency and control over our own lives. Everyone in the movie is characterized as the sum of their own agency and the influences that act upon them. Time travel allows the narrative to collapse the temporal dimension and superimpose the self as actor and the self as consequence.
JGL 'wins' by understanding that the thing he has always valued as a lifesaver (a man who takes a lost boy and gives him a life) is in fact an ultimately destructive force. Through the Rainmaker he is able to confront the long-term repercussions of a culture of masculine violence and choose to avert them.