Should I report a seemingly psychotic group of underage women?

I read a question on here that is really making me want to report the one/one's who asked to the police. Here is the question that was posted on here from user x KaT x "6months ago i (15) met a guy through a friend at a party. he gave me a ride to pick up my friend (16) from a concert. he seemed allgood and we thought he was 25. we got invited to a party at his house about a week later. so we went. he supplied us various drugs and was starting to seem a bit dodge. about a month later we find his ID and it says he is 35years old. He started to hit on us and sent my friend inappropriate messages and was clearly trying to get something from her. His 29 year old flat mate tried to have sex with her, and the 35year old continued to supply free drugs. to keep us coming back. we slept in his bed with him once or twice, and hung out with him about 10times. He was obviously a creep, now- 6months later. weve decided that were going to get something from this, to teach him a lesson, we asked him for 6grand, or wed call the police on him. Obviously he'll be looking at a much worse punishment then we are, considering were under 17. what can go wrong with this scenario? what should we do?" So what do you think?