There's two obvious "legitimate" reasons to use credit: to smooth out expenditure volatility (a big purchase like a house, an emergency) and to smooth out income volatility (a temporary lack of a job). If you are suddenly sans job and living on savings/unemployment/charity etc., but have a perfectly reasonable expectation of long-term average income much above your short-term situation, financing a burrito makes sense--you’re being cash-flow efficient (extending your runway, if you will)

Also, in my personal experience, a new job often brings various costs (food, clothes, transportation, relocation, etc) long before the paychecks show up. There was a time in the early 2000s where being able to klarna a tank or two of gas until my paycheck landed would have been extremely useful to me