If OP's friends care about privacy, decentralization then they won't care about altcoins, clearly what they want is just to find a high return investment. And for those who are only interested in profit, explaining the use cases and advantages of bitcoin is useless.
How can people understand the level of privacy if the investment they are making is only based on something free and it doesn't align with what they say because at some point they will try to verify their identity to claim the given reward.
That's what happens generally and I even see such people willing to do KYC just to claim the given reward.
If I were the OP, I wouldn't waste time trying to convince or argue with them. Instead, I will let them experience the market themselves and after gaining experience, they will realize for themselves what are the best investments they should be interested in. Because everyone has different views, visions, thoughts and everyone has a big ego, so trying to convince others is not a wise idea. Let them experience it for themselves to learn the most practical lessons.
After being given advice and they don't want to listen then it would be better to leave because I'm sure there are many things that can be done compared to convincing others with limited knowledge.
People will see experience as the best teacher and there are many cases that may have happened in the crypto space, so it will be an evaluation that can be done to develop themselves to be better in terms of finance.
If they are not closed to the sophistication of technology then I am sure there are many sources that can be learned, especially for the best investments in bitcoin today.