Maybe a good moment to commemorate the infamous RedTubeGate from 2013 in Germany:
A couple lawyers and fishy business men launch an ad campaign on RedTube. Through that advertisement they collected IP addresses of visitors.
Before launching that campaign they allegedly bought the rights for three cheap porn flicks.
Now they also claim that they have some miraculous software which allows them to track who has been watching those flicks on RedTube. They even get a totally unclear blueprint for that software officially certified by a surveyor. [4]
Then they appeal to a court in Cologne for the real world addresses corresponding to the IP addresses arguing they can prove those poor schmocks watched their illegally uploaded crap flicks.
Suddenly thousands of people receive letters threatening legal action if they do not agree on paying a fee of 250 Euro. Many people comply out of fear for their reputation and just pay.
1: https://web.archive.org/web/20140822000304/http://www.wbs-la...
2: https://www.joyofdata.de/blog/tool-visualization-connections...
3: https://web.archive.org/web/20140911214044/http://www.cracka...
4: https://www.abmahnhelfer.de/wp-content/uploads/2013/12/EV.pd...
(many of the original sources have been deleted and are only available through archive.org)