To me, it is risky either way (existing product or no product), and when I decide to invest in a project, even if I take the time to research, I am aware there is always the chance of losing. Of course it gives you more confidence if there is already an existing product or prototype. Unfortunately, with digital goods sometimes it can be hard to tell if they will be as efficient when they are officially launched (having a beta test is not the same as having millions of users accessing a platform), or they might be worried someone will try to copy the idea (not that we don't already see plenty of ICOs offering the same). Having a product also doesn't guarantee they won't scam you later on (it can just be a more elaborate scam).