I believe I read V and MC see AAPL as a bit of threat, however, Visa also does contactless payments, and they collect fees rather than extend credit. They provide the card system for financial institutions to extend credit and then collect fees from it. Apple is probably trying to get in on those fees, rather than offering their own credit card. If they offered their own credit card, it'd probably be backed up by some bank. So no, AAPL offering a credit card wont bankrupt them