Credit cards are more convenient.

1. Double tap power button on a phone you are already holding

2. Tap the reader

Versus

1. Find an ATM

2. Take your wallet out of your pocket

3. Take your card out of your wallet

4. Spend a minute withdrawing cash from the ATM

5. Put the cash in your wallet

6. Put your wallet in your pants

7. Go to the actual place you want to spend money

8. Take your wallet out of your pocket

9. Take cash out of your wallet

10. Hand it over

11. Wait to receive change

12. Put the change in your wallet

13. Put your wallet in your pocket

If you want cash to make a resurgence you need to figure out how we can make a digital version of it.