From offscreen in an IG video, Cardi explains that she doesn’t watch a lot of movies, and therefore has quite a few questions in the first quarter of Bird Box. “Where are they swimming to?” she asks. “Why she in the river?”
About halfway through the film, a frustrated Cardi questions what everyone is "seeing." “What are they seeing bro? What’s making them want to kill themselves?” she asks. “I don’t fucking get it. Shit is getting me mad.”
Then the “Money” rapper presents a brilliant theory: “Are they fucking seeing their bills? I think motherfuckers is seeing their bills and that’s why they wanna fucking kill themself.”
It's explained at one point in the movie (sorry if you haven't seen it yet, you'll be alright) that the monsters somehow show victims their greatest fears. With that in mind, Cardi's theory makes perfect sense. What's more terrifying than your rent or car note? Everyone else seems to agree.