OK but why wouldn't you cut out the user as a middleman, and just market to the user directly? If I knew you were a fan of Nike, I could just sell that to Nike

OK but why wouldn't you cut out the user as a middleman, and just market to the user directly? If I knew you were a fan of Nike, I could just sell that to Nike directly instead of asking you to in a roundabout fashion. As many people have observed, the current digital economy really already facilitates you monetizing your data, by allowing you to have access to innumerable resources for free. Those resources don't cost zero to operate, but you pay for them with your data.