Yes, obviously these apps are earning from other means, else how will Phonepe have a revenue of 5000 cr. UPI is basically the customer acquisition tool for these companies. And once the customer is onboarded on these apps, it is a goldmine for cross selling and up selling. Imagine the amount of data these companies can process which includes bank details, transactions, purchase patterns, credit scores, and what not. Loan and insurance companies would beg for such a database.
So basically
UPI = Customer Acquisition
Other Services = Sales and Profitability.