Nightcrawler is a movie that tells the story of Louis Bloom, a strange, opportunistic, amoral guy who is making a living at the outset by stealing metal objects - manhole covers, fencing wire, etc - and selling it for scrap. He happens across a crime scene and a freelance video photographer - a stringer - who sells footage for money - and the course of his life is set.
It would tempting, and easy, to see the movie as a morality tale about tabloid journalism. We see the stringers earning a living by rushing shots of people on the worst day of their lives to the TV stations, who with equal amorality decide which shots to play on the news that night. Some of the characters, Rene Russo's news manager being the prime one, are seen consciously deciding to dump their ethics to keep a job.
The main object of the movie is our own fascination with the worst things that we see in the world, and our constant desire to find out more about even the most grotesque crimes and accidents. We see the things that Louis films as he sees them - through the lens and on his viewscreen, and on TV. It makes us, even against our will, want to see more, exactly the way that TV does. Also, we see life in Nightcrawler the way that we increasingly see our own lives - on the screen of a phone as we document the minutiae of our own lives, or as we watch Youtube.
There is no preaching in the movie, no statements about the 'media machine' or 'the public's demand to see.' All the characters make their own decisions, albeit under sometimes grossly manipulated pressures, but all are shown as responsible for their actions, and acting out of their own motivations. Louis' assistant is pressured by him to take part in shockingly amoral behaviours, but then manipulates the situation to extract more money from Louis.
Louis Bloom has a disturbing veneer of business speak over his obviously selfish actions; this is perhaps the most disturbing aspect of the whole film. He never speaks crudely, even when making crude propositions; everything he says is couched in smooth business phrases and comes out in an almost silky, oily diction. Coming out as it did in 2014, and obviously in production for some time before that, you can only wonder at the depiction of gross immorality in everyday life covered up with the fake respectability of business jargon, and how this jells not only with the recent US election, but with the domination of business as a legitimate pursuit at the cost of human values in general. From this point of view, Nightcrawler works as a warning about the cost of making a living at the expense of our conscience.