In my opinion the communicating app or the platform should be responsible for it, it can prevent them registering on it, I know it’s difficult for them to recognize who is a fraud or not but it can banned the account who was complained by other accounts, that can clean the app’s environment, as a consumer we should be alert , if someone tends to speak sweet words to you , or someone tells you that he or she can help you make a sum of money, don’t fall for it , since they just tempt you to commit a crime or they want to cheat your money , keep in mind penny wise pound foolish