Cold-calling means their victims did not know them before and they offer the investment of high yield return. Easy to know they are scammers but some people are ignorant and lack the knowledge to know that they are scammers.
This is where they always fail it, every investment of high yield withing a very little time frame is an obvious scam cooking, people are very greedy and insensitive in their decisions to patronize these investment platforms.
Another good virtue is always to try verifying the authenticity of their identities, I have been called for a job opportunity and when I got the details of their proxy companies, I searched for them and the names they gave me contradicted those on the company official website and LinkedIn page. I you can spare a minute or two to verify both certificates, existence and authenticity of identities tendered by anyone offering you an opportunity and even their communication channels, you can be sure to skip about 90% of scam attempts.