Every investor wants to profit amidst all things. Majority of investors are attracted firstly because of the ROI after which they will now look deeply into what the project offers. For the sake of scamming, no one wants to be a victim of such so it's better to have your money and profit early and know what you are left with after after sorting out things.
You're right, we want to earn and not be a victim of scam at the same time. Well short period to earn is really good but is it real? Most of them are not specially if offering a high return. Nowadays you need to conduct a research before entering in an investment because its your hard earned money that you will put at risk to somehow gain from it thus dont aim for high return in short period because its likely a scam.