It's entirely possible that sending the audience out feeling lousy was intentional

A great movie, one of the best of this year. There was a bit of confusion at one point in the plot, but nothing serious.

One of the film's great tricks is that, for a time, you think it will go down a rabbit hole of unrealistic glorification.

While it is a pity that the story wasn't told with more visual finesse, this is trivial compared to our real-world problems. It takes a good movie to put that into perspective.