But even if they never saw a penny of income directly from me, what they would still get out of it would be the data. And insight into the purchase habits of consumers with plenty of expendable income - the same people that would otherwise be a losing proposition for a business that actually relied on failure to pay on time to stay afloat - seems like it'd be far more valuable than the entirety of what they'd be able to squeeze out of the already-cash-strapped.
I'm actually highly impressed at the extent to which they're completely successful in focusing the public discussion on their "outrageous" and exploitative policies. They put on a thoroughly convincing show of fighting tooth-and-nail against regulations to reign in that behavior. But I think it's because, if it ever got seriously done, people would start asking how it was they were still in business - and they would definitely still be in business. But the finance operation is just how they collect the raw material for their actual product.