Several states already ban payday loans and some don’t allow lotteries (let alone state sponsored lotteries that are used to fund things like education). Personally, I think setting an effective interest rate cap (including loan fees) at around 15-20% a year would be very effective at preventing the kind of lending that can lead someone to multiple years of high-interest debt repayment or eventual bankruptcy. More education in high school about how to manage your finances wisely could also prove beneficial.