If someone is offering you something for nothing it is a scam, period. And as people have pointed out when something is indistinguishable from a ponzi scheme then for all intents and purposes it is one.
The fact you use "low risk" in your advertising is yet another red flag.
Your thumb rules will not be always right.
As I will eat the first 20% loss, it is low risk.
No it is not. That just means your customers will have a hard time judging the real risk involved in your offering. "low risk" is not 2% returns a week from an anonymous identity on the internet it is a term deposit at a physical bank backed by insurance, as crappy as that may be.
Your offering is the meaning of "high risk".