From the discussion of revenue from websites with online tests on RSDN:

XXX: I’ve always wondered how much profit such a site brings.

YYY: I worked in Miami for a company that creates such websites. The database contained thousands of similar sites, thousands of domain names, hundreds of registered corporations for dismantling legal claims. Annual profit of $200 million in the year. The staff is about 200 people plus about 100-200 remote employees. The company exists for 3 years. The information collected about users was used for the company’s own marketing purposes and sold to thousands of subscribers. One thought on “Are you a diabetic?” So the time between the answer to this question and the call from the operator with the offer to buy medicines for diabetics, did not exceed a few minutes.