When you open a credit card your revolving line is often bundled with others and sold into a marketable security, the same as mortgages, auto loans, etc. The card issuer earns a fee for creating the pool of accounts, and is paid for managing the accounts.

To make an attractive security the issuer needs a mix of customer characteristics. Customer with high credit scores help lower the average default risk and they generate some merchant fees. This is useful even if you don't pay finance charges (finance charges include more than interest), but others in the pool will.

Separately, Chase will receive incentives from VISA for meeting targets for number of accounts opened, aggregate transaction volume, etc.