From your clarifications in this comment, it doesn't sound like you're the type of person I'm talking about. I don't disagree at all that loans can take advantage of people's innumeracy and desperation-driven irrationality. And I consider this a serious concern with excessively high rates. But it needs to be balanced against the bedrock principle that taking a choice away from someone usually immiserates them further, and if you believe otherwise you need a damn high level of rigor to show it.
Tarring the payday loan industry writ large as a scam doesn't stand up to that level of rigor, and there are a thousand qualitative and quantitative pieces of evidence pointing to the fact that the industry does provide value to a portion of the underbanked population.
This doesn't preclude things like capping rates, but this is an explicit recognition that, at the given rate, the cost of the innumerate being taken advantage of is higher than the cost of cutting off an emergency lifeline for people who can use it rationally.
I don't think you and I are especially in disagreement here, given your clarification of what you meant by "scam".
Maybe I was being a bit hyperbolic when I said "scam" since they usually do what they advertise. Let me rephrase: they have ridiculously high interest rates that can lead to difficult-to-escape debt, and they are predatory towards desperate people, hence why you usually see them in poorer neighborhoods.
Debt is absolutely a tool and I wasn't claiming otherwise, so when I said "scam", what I really meant was "the worst possible way to leverage debt".