While you are right to warn people, it's a good idea to give some details so that it's more than just your opinion ...

https://cointelegraph.com/news/another-day-another-scam-ecoin-plus-disappears-with-investors-cash

Always be vigilant when investing, and look for signs of bad dealings like;

Pay to recruit
If you are paid to sign people up, always look closer at what's being offered

No identifiable product or service
If there's nothing for sale, where is the money coming from? You!

Anonymous or fly-by-night e-mails
Is the person you're paying running the operation from a hotmail account? Why didn't they spring for a domain?

Domain details "Protected"
If there's not a business address tied to the domain whois, consider this a BIG RED FLAG