[rrrrrrrrrrrryan]

Fraud protection, mostly.

If someone steals your debit card and spends all your money, you might very well be fucked.

But (in America) if someone steals your credit card and spends a bunch of money, they technically stole money from the bank, so it's the bank that might be fucked, not you. All you have to say is "yeah that wasn't me" and the bank reverses the transaction.

If you're blatantly abusing this the bank will end their relationship with you and cancel your card, but that's pretty much worst case scenario, and you won't be on the hook for anything. And they obviously make enough money off of people who carry a balance and pay interest that they still come out way ahead.