Just think about BNPL for 3 seconds. How do they make money? By selling people shit they can't afford, waiting for them to miss payments, and charging hefty interest and fees – sometimes totaling up to as much as the product itself.
You can argue "it is legal" "they signed the contract" "they should have known better” all you like, but just like payday loans it is a social ill that we need to deal with.