such as?
The payday loan industry, for one. They're designed to get you into crippling debt. Regular loans as well, since being poor is bad for your credit score. Massive healthcare bills, since if you're hit by a car you don't get a choice in going to the ER and you're getting the bill whether you like it or not, plus you'd be unable to work and make money while in the hospital in order to pay off the huge bill. When you're poor and constantly struggling to make ends meet, a sudden large cost (such as a broken car, sudden injury requiring hospitalization, theft, etc.) can drive you further into poverty very easily.