The people seeing the adds aren't the consumer, they are the commodity. The value of an ad isn't just in selling a product. Ad networks are great at collecting behavioral data. That data is quickly becoming more valuable than the products in the ads.

If I click on an ad for funeral services I might buy something but probably won't. But I may have just confirmed that a close relative just died. That factoid is worth something to a great many people beyond the local funeral parlor who paid for the ad. I should expect real estate agents and quack financial advisers to be knocking on my door by the end of the day.