After gathering all those informations from them I wanted to explain to them how what they are into is called a Ponzi Scheme and how it can crash at an instant and they lose their money and that it's a syndicate of scammers that's hiding behind the platform waiting for the right time to elope. I felt like talking to them about bitcoin and how's of guaranteed security than any of those schemes or cryptocurrency. But when I looked at their countenance about this socalled scheme I was moved to hold my peace and let them learn from the hard way, as it will be more understood by them if they learn that way maybe they will give audience and interest to bitcoin when I'll have to introduce it to them after they must have been stinge by the KDB Ponzi Scheme.
I don't think you actually did the right thing by not warning them of the dangers that lies ahead. You would agree with me that it's not everyone that's well enlightened about the ponzi schemes, some persons are easily swayed by quick money that they don't pause for a second to think or do diligence before taking any action. So you would have done your part by warning them and if they fail to heed to your warning then it's up to them to suffer the consequences.
I think it would have been an inappropriate time to educate them about Bitcoin, they might think you introducing Bitcoin to them is the main reason you want them to abandon ship. Just give them some time then you can enlighten them about Bitcoin but you really need to give them heads up about ponzi scheme.