That much-repeated factoid is the result of sloppy, clickbait reporting of a lousy survey.

People were asked "If you had a sudden $500 expense, how would you pay for it?" with options like ["cash", "checking account", "credit card", "pay-day loan", "borrow from family"] and unsurprisingly many people said "credit card". This then got repeated and reported as "Americans can't pay $500 without going into debt".