At a 2% processing fee if you spend 40k a year that's already $800 in revenue for the issuing bank. I don't think that's trivial for a single person.
You also need to take into account the bank's cost of funds, the cost of administering the account, the cost of fraud, cost of disputes (do you ever do a chargeback?)
The marginal cost of servicing another person when they already have a consumer base of people with debt is very small (close to zero). I'm trying to say it's still profitable, but not where they make the bulk of the revenue.