When the job that supports all this disappears and he struggles through a series of embarrassing failed job interviews he becomes quite untethered. Eventually as it looks like the house is going to be repossessed Man-su comes up with a solution: eliminate the competition.
Pre-emptively, and permanently.
CW: some violence, DIY dentistry
Park Chan-wook's serial killer black comedy is a complicated layered beast.
A lesser filmmaker would have had Lee Byung-hun go badass and tick off a list of victims, which we know he can do, but here he's the everyman not really up to the task.
It's full of internal callbacks, the phrase "no other choice" keeps popping up and his first "victim" is a man he shares much in common with. Man-su tells him he should have listened to his wife and got a job in a café when he too made essentially the same mistake.
The kids have tangible reality about them rather than being just props and while Man-su flounders Mi-ri gets on with doing what needs to be done and cuts the fat from their lifestyle.
There are moments of surreality, slapstick and farce, Man-su gets jealous of Mi-ri when she goes back to work and there's even an almost dance-off.
Meanwhile the core theme of only getting worth from your job and how you'll do anything to screw over and exploit other people only to have it done to you is there all the way through it. Without ever interfering with all the fun quirky murdering. Nobody ever had any other choice.
This is up there with The Handmaiden, 9/10.