If you're expecting to gain from every ICO that is out there, that won't happen. As you said most of the ICO's out there right now are useless, they don't offer anything significant and that's why they are valued eventually to zero. But that's up to you to know before you invest your money in it. You can read the project's whitepaper and talk with the community of even founders about it, so there is no excuse of getting scammed. Of course you can't foresee everything (see what happened with Tezos, who would have thought that), but you can evaluate a project carefully enough to be at least somewhat more sure that it won't scam you of your hard earned money, I guess it's a learning curve and eventually people will understand how it works.