yes the fact is like that, in this crypto industry there is no full guarantee for you. Even in traditional investment, nothing guarantees you profit. There will be no certainty in future income, and if a project claims their tokens will become more and more expensive over time, it is very likely that they are lying. Of course, that does not mean that they are wrong, however, ensuring that everyone in the inevitable benefit is not responsible, to say the least. If you see a project that claims that your profits will grow tenfold in just six months, it's far more likely to be a good old Ponzi scheme than it really is, as seen in BitConnect.
So, no matter how this promise actually looks, if you see that the project offers you sky-high profits for literally no effort, it probably means that they want to make that profit out of you.
yes, you are right to say, there is no full guarantee when we work on a project, whether they will keep their promises or not. You say that a project that promises huge rewards without effort is too easy, it is possible that the project just wants to take advantage of us. even for a project that promised to give reasonable rewards, many also lie for now. therefore we must be good at doing research first before we participate in a project.