<https://www.theguardian.com/commentisfree/2017/oct/08/facebook-zuckerberg-in-a-hole-data-mining-business-model>;

[...]
Facebook, like Google, is an extractive company, rather like ExxonMobil or Glencore. It “mines”, refines, aggregates and sells its users’ personal information and data trails to advertisers, who then use it to target ads at said users. This data is clearly valuable. At the moment, for example, the company earns nearly $20 per user per year (in the US and Canada, anyway) by monetising their data. The downside – from society’s point of view – is that the targeted system that delivers these revenues is easily manipulated by political actors – as we saw from the way Russian interests used it in the 2016 election. [...]