I think they understand that Bitcoin or any sort of crypto coins just becomes the instrument to do the said scheme, and not that they're purely scam as a coin.
This is a common misconception for people these days that anything inside the crypto space is scam and everyone sitting inside the crypto space are scammers.

About the platform you mentioned (Forsage), it is quite getting promotion lately in Facebook with one of my friends as they invested in ETH. For now I haven't seen an update, maybe he cashed it out when he found out that the platform is a ponzi scheme, who knows? 
This is why I don't trust a lot of people in Facebook when it comes to crypto plus their referral passive income bs.