What you need to understand is that there is no free Bitcoin anywhere, so any platform promising you free Bitcoin is a scam. Mind you, it's not that difficult to identify a ponzi scheme, any platform promising you free Bitcoin or unrealistic returns on your investment without a legitimate revenue is a red flag so avoid them.
Instead of putting your energy into looking for platforms that will offer you free Bitcoin or unrealistic returns, why not focus on the ongoing accumulation of Bitcoin and accumulate it little by little, and before you know it you have accumulated a large amount of Bitcoin to hold for the long term.
Yes, I agree with you. No free bitcoin anywhere, you have to earn them. But let consider the fact that Op is talking about newbies and to be honest, some of them don't know how to verify a legitimate platform with a legitimate revenue. It might be easy for us to identify a ponzi scheme when we see one but newbies don't have that experience yet. They see platforms offering high returns as an opportunity to earn more not knowing it's a red flag.
My simple advice for them is to keep profit aside from the beginning. Anything related to profit, free bitcoin or double your investment, they should stay away from them and focus on just accumulation until they understand the game very well. With time, once they understand the game they'll naturally know how to spot a ponzi scheme themselves unless they allow their greed to make decision for them.