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. Because from their expressions there's nothing I will say at that time negative of the scheme that will sound truthful or make sense and I wasn't ready for argument neither.
I do want to know if my idea or decision on this is the right way?
Honestly, your decision is the right plan.
Firstly, this person is your brother and I believe you know him more than us.
Secondly, there are some people that won't listen to you in this type of situation because they believe they are making the right decision and the best way to get their attention is after they have made the mistake.
And also have you come in contact with people that invests their money in any ponzi scheme and tried talking them out and what was their response ?
Yes, I have been in contact with people who invested in the Ponzi scheme and they don't always listen to advice given to them because the cool easy reward of the Ponzi scheme always blinds them from the fact until they lose their investment.