Earlier quoted context omitted.
They already do it. Credit Card companies like MasterCard and AmEx have been selling data to advertisers for at least 8 years now. That plus all the data you can extrapolate from other sources can give anyone an accurate picture of your consumption habits.
Is this in their TOS? Do you know whether one can opt out? Are there any electronic payments schemes that (excluding the e-coins) don't share consumption data?
You probably can find similar pages for other companies.