I want to categorically tell this set of people that Bitcoin is the way forward for you, bitcoin works for everyone, and the system was designed in a way that every interested person can participate.
Bitcoin allows you to be your bank and be in charge of your money with no interference from anyone. Participation is dependent on your interest, not your identity, that's to say that everyone can be involved without their identity known. Note that blockchain technology guarantees your Bitcoin security, so don't be afraid just give it a trial but with a little money I believe you won't regret it.
In case you are one of the persons that store all their money at home in a big vault, you might be reluctant to transfer all your money into bitcoin. The upside of having fiat money at home is that you can see it, touch it and even when the whole world breaks down you will probably find other people that are willing to trade with you for that money. Making now the switch to a fully crypto wallet can be a hard step for people that are so used to using cash in their daily lives. I would recommend to not move too fast and rather slowly ease into the crypto community. Why not start with building a crypto portfolio with 10-15% of your wealth and slowly build it up over time. Bitcoins are a good currency to store value online, and its also a great opportunity to make some money longterm. But I wouldn't recommend to put all our money into one single asset class, better to spread it out and diversify in multiple different assets.
Is it safe for those who have a lot of fiat money and keep it in a vault at home instead of depositing it in the bank? Of course not. But if fiat money can be converted and transferred to bitcoins then it can certainly be safe if he can store the bitcoins properly. A person using a vault at home worries about the safety of their money when they go out, but a Bitcoin investor can be completely safe from such worries. For a new investor I would agree with you that he can keep 10-15% of his wealth in Bitcoin. After that if he feels, it can bring benefits to him then he can increase his portfolio as per his wish.