Bird Box came out in 2018 on Netflix and stars Sandra Bullock as a soon-to-be mother who is fearful of the future thanks to a complicated past. The monster in the movie is never revealed, though there were some special effects designs created as a test (thankfully they were not in the movie). This is another one of those films where it is very open-ended and up for interpretation since it is not fully explained what hunts the characters. But what would drive someone to commit the tragic act of suicide? Here are a few possible answers that might make rewatching Bird Box a little more frightening.
In the movie, Sandra's character Malorie embarks on a mission to take her unnamed son and adopted daughter to a safe haven away from the creatures that stalk them. They have to remain blindfolded because if they even look at the unseen being for a second, they will die. There are several characters introduced that are either insane, blind, or criminal that are immune to the threat. Those who have seen whatever the monster is are heard saying how 'beautiful' it is and how they want others to open their eyes to its majesty.
One theory of what the monster is could simply just be a metaphor for the fear of becoming a parent. Sandra Bullock explained that her interpretation of the film is of a new parent trying to guide her children through a scary world while she herself is not sure where to go or what to do. Parents often will shield their children from the horrors of the world whether it be bad people, death, or fear. Putting on the blindfold symbolizes a mother trying to protect her own family against some of the nasty things the world has to offer. Malorie fears that if she does not prepare her children well enough for the future, they might one day decide it is all too much and commit suicide.
A bird box is also referred to as a nesting box. Birds can have a safe place away from the dangers of the world and harsh weather in order to raise their young and have a home. But even though they have a safe place to live, being trapped inside a box is more about survival and less about enjoying life. This explains why even though Malorie needs a safe place for herself and family, she feels like she's trapped in a box unable to fend for herself. She feels she is burdened by having to protect these children. Of course by the end of the movie she realizes that she loves her children. They are not a burden but a reason to live.
To make things a little more sinister, perhaps the monster is a large god-like being so big and powerful that when a human sees it, they cannot comprehend what they are looking at and go mad. The author of the Bird Box book originally said his idea for what the monster was is the representation of infinity. Something so grand and beyond our little, insignificant lives. The embodiment of infinity, in the form of a shape-shifting god, is not something a human brain is capable of processing and therefore if looked upon, causes people to escape their reality in the form of suicide. Infinity is and always was, and therefore will always be. The drawings that Gary made suggest the infinity monster is a shape-shifting Lovecraftian being.
Another theory could be that this is a rapture of all people that God sees fit to join them. There are several characters that say things that sound like whatever they are looking at appears to be a dead relative. They even say things like "it's not so bad" when they finally see it. The monster even uses voices of people who have died to try and convince those still alive to open their eyes. This is because the monster is an embodiment of all of the good souls that have been raptured. They are trying to convince others to leave their flesh and bodies in order to join them.
It's no coincidence that right after Tom saves Malorie and her children that he is 'raptured.' He has done his good deed, sacrificed himself, and god sees him as worthy of being 'saved.' God, in this theory, is encouraging people to lift the veil from their eyes and accept them. But, all god can do is knock on the door and cannot force themself inside. That is why all of the people left on earth are either keeping their eyes shut, or they are bad/crazy people. Criminals are the only ones who have not been raptured.
This could also all just be a representation of mental health. Those who have been dealing with their demons their whole lives are immune to the mass depression; while those who have been keeping themselves blind to their troubles are now forced to deal with them. Whatever the monster is, it's a good thing the director chose not to explain it.