I also thought there was a bit of optimism and humanity in that final scene, but that just made the rest of the movie more depressing. I thought the film was kind of like an American Psycho for the 2010s (but less funny).
I'm surprised at how thoroughly mainstream critics hated this movie. It's unpleasant, certainly, but most critics didn't seem able to discern a separation between the movie's POV and the protagonist's POV. Could it just be that they were disoriented by the title of the movie? I do think that the title was rather self-sabotaging (though that keeps right in the spirit of the film, I guess.) It makes it near impossible to google, and misleads expectations.
Does anyone have any good theories about the title? I heard someone (maybe Julie Klausner or Marc Maron) ask Heidecker about the title, but I don't recall him offering a satisfying explanation.