yes "selling the data" is a oversimplification. but "they sell access to your data to other companies, that also have a significant base of user/customer-data,

yes "selling the data" is a oversimplification. but "they sell access to your data to other companies, that also have a significant base of user/customer-data, and this let's those other companies correlate your identity/profile" is just not as catchy or understandable.