You're very correct but not in the way you might think. They are reselling the consumer spending data (timestamps, store/merchant, dollar amounts, demographics

You're very correct but not in the way you might think. They are reselling the consumer spending data (timestamps, store/merchant, dollar amounts, demographics about the consumer, etc) to hedge funds, investment banks, and as competitive intelligence to other companies. Imagine detailed consumer spending for Home Depot & Lowe's for the past few years broken down by market, average purchase size, frequency, churn rate, loyalty, demographics of consumer, financial position of consumer, credit scores, et al. That's huge if you're investing in either company or if you are either company and you want to know how your competition is faring, marketing spend, expansion decisions, etc. In their earnings they only show direct Mint.com revenue (affiliate traffic from signing up for credit cards, bank accounts, mortgages, etc) which is extremely small compared to the data intelligence. The rest probably shows up in "data services" or something vague.