I think it's true in a weak sense. If the customer is paying, that is one revenue source. If you sell data, that's a second revenue source. Adding the second re

I think it's true in a weak sense. If the customer is paying, that is one revenue source. If you sell data, that's a second revenue source. Adding the second revenue source might be worth it since it can increase profit. But it also adds business risk. Your customer might jump to a competitor that charges money but doesn't sell your data. Of course, that assumes competition is effective, which requires consumers to be informed that it's even a potential issue, to care, and to be able to assess which company is better or worse.