Nobody capable of high school level of math and with access to a credit card should rationally want to use BNPLs, at least in the US:

Credit card payments have an average payment due date of 6 weeks (0-4 weeks until statement cutoff, 4 further weeks until payment due date without interest charges), no interest charges when paid within that timeframe, and offer around 1-2% of cashback.

BNPLs have 25% due at 0, 2, 4, and 6 weeks respectively, for an average due date of 3 weeks, and usually don't offer any cashback. In other words, you get half as long to pay back the loan and miss out on 1-2% of opportunity cost on top of that.

The fact that people still use them shows that either some consumers value other things more highly than just the strictly best deal from a financial point of view, or is a concerning piece of evidence of a lack of financial literacy (or both).