Credit cards and bank/debit/ATM cards count toward "sufficient money", if you have the money in your bank account or credit limit.

You would be surprised how many people show up at the border with:
1. No evidence of any place to sleep past their first night
2. No bank cards
3. Carrying, at most, several hundred $ in cash (sometimes for multiple people)

In cases like that, CBP will challenge whether the visitor can support themselves without working. That is why there is financial support requirement.

If you think this is something you might be questioned about, bring bank statement or credit card statement, or maybe letter from your friend with name/address and number of days you will stay.