There are some really obvious movie tropes that can make films predictable. One involves the main protagonists having everything work amazingly in the beginning before something happens that casts new light on their circumstances. It's at that moment in a film where the real action starts - where the plot takes shape and now you're getting a sense of what this movie is actually about.
So in this movie, you knew that the fact that the Kim family was able to essentially con their way into their new gigs was too easy - that there was going to a "twist," for lack of a better word, that would change the narrative. That isn't to say that first half wasn't humorous - it certainly was - but you knew it wasn't meant to be. It was clearly set up for a twist when they were chilling in the house while the Park family was out camping. It was dark and they were getting tipsy and everything was going well and then *DING DONG* the old maid is outside. And from years of watching horror movies, you know the old maid isn't just there on some sort of friendly mission - that she is going to reveal a secret that changes the whole trajectory of the story.
And so she does, revealing her husband-in-hiding in the bunker. Okay, that's interesting. Where is this story headed?
Inevitably, the Kim family's deceit is revealed to the maid and now she's holding them hostage. They overpower her and her deadbeat husband and toss them back into the bunker.
So, at that point, the obvious conclusion is that they won't just stay down there - they're going to be a factor in this story. And inevitably, the husband gets out and a bloody melee ensues (including the Daddy Kim taking out **** Daddy Park in some PTSD-like reaction to complaints about body odor). And then Daddy Kim goes and hides in the bunker. End of story.
Really? That's all there was? That's what we were building up to? Yes, there are these themes of class warfare present throughout. But there was nothing "notable" or "profound" about that from my POV - nothing that's going to make me consider this the kind of movie that deserves an BP nom at the Academy Awards, let alone the kind of movie that will stick with me for a long time.