Most of the scam because of Ponzi & Fake ICO.
Scammers are stupid. Only victims are more stupid than scammers or very greedy and can not control their actions. At the ends, they get scammed.
Not everyone have the same knowledge & experience with other people, and everyone not always coming on bitcointalk.org before they know about the cryptocurrency or bitcoin. They started visiting google finding new article, the capability went they learning also not same everyone can learn fast & understand the other people can slowly to learning & understand so they need to make sure with someone who have more knowledge with him.
For example like me, if you want to see my profile i have some gap activity went i register to bitcointalk forum. With the gap around 9 months, it that times i learning cryptocurrency and other relating topics about bitcoin with my group telegram went we looking mined altcoin. Then went i comeback to bitcointalk i already have basic knowledge about trading, investment & scam attempt for some project/platform.