Where exactly does the return come from?
The first question knocks out half the cases. A return comes from rent, from interest, from operating profit, or from a capital gain. If the answer is a vague word — "trading", "arbitrage", "artificial intelligence" — with no document behind it, the conversation should stop there.
Who holds the money, and who can move it?
A serious investment separates the manager from the custodian. If the same person decides on the trades and holds the funds, your capital is protected by nothing but their good faith.
What happens if I want out tomorrow?
Ask for the withdrawal terms in writing, with timelines and penalties. Fraudulent schemes work as long as few people exit; so they make exiting expensive, slow, or conditional on recruiting others.
The most reliable signal remains recruitment
As soon as a significant part of your income depends on the people you bring in, you are no longer in an investment but in a pyramid. That single criterion, applied seriously, protects against the overwhelming majority of losses we see in consultations.