Based on the fact they were targeting Sanders, Trump, and Stein voters I imagine they were probably just making money off of clickbait with advertisements on their pages. It was election season so naturally most of the clickbait farms transitioned into politics rather than 'how to get an 8-pack' or whatever other health/lifestyle garbage they were peddling before.

That buys a lot of impressions, but not much compared to the $5 billion in advertising that was also spent on the election.