"Companies like Facebook and Twitter are poorly policing automated bots and other methods for manipulating social media...

For €300, the researchers bought over 3,500 comments, 25,000 likes, 20,000 views and 5,000 followers...

After four weeks, about 80% of the fake clicks remained. And virtually all of the accounts remained active three weeks after researchers reported them"

https://www.nytimes.com/2019/12/06/technology/fake-social-media-manipulation.html