How to inform mom’s boyfriend he’s getting scammed? Amway

Long story short my mom’s boyfriend and his daughter haven’t talked in many years due to a fall out but patched it up recently. He’s really happy to be in her life again but she (his own daughter) got him into Amway. He doesn’t know about these type of things and I just found out because he asked me to register. I believe she reconnected with him only to scam him. How should I break to him?