Bitcoin is available for them to buy it and hold it as their own investment. They don't need to join any investment program with high promised profit. Investment has risk, risk of loss and if any program guarantees you about profit, you should smell a scam attempt.
However, people want to have profit, guaranteed profit and they don't want to have risk. Unfortunately, with this mind, they choose to join Ponzi program and get scammed.
But if they just buy bitcoins and hold them in their personal wallets, the chances of them being scammed are slim because as long as they can guard their personal wallets, that won't happen. They also have the opportunity to sell their bitcoins at a high price on a later exchange.
In essence, never involve other people's money for any offer, just buy and hold it is the best for us to start long-term investing in bitcoin but the rest if there is a program from a company offering investment in bitcoin it is clear he will start with his fraudulent actions .
We must give them advice not to fall into that trap and not be tempted by high ROI gains.
It's about how we can keep the money we want to invest and not be easily tempted if an investment program is too good to be true. And if they have bought bitcoins, it's better for them to keep them than to invest in programs we don't know the truth of.
If we encounter this thing with our family or friends, we should warn them and advise them not to try to join because it will only trick us later.