It is not too difficult to do this, buying bitcoin and storing it in a non custodial wallet by themselves. It will force the investors to learn about wallet, backup, recovery and security of wallet and their devices. It requires some time to learn basics but in security and safety of their money, it is very worth to do.
Recommended Bitcoin wallets.
Security checklist
Protect yourself from fake wallet software (guide)
WARNING when using mobile device wallets (Android, iOS)
This may seem easy for young people with basic computer knowledge , but what about older people , who have difficulty with today's digital devices? I think bitcoin ETFs can solve that problem and it works in this case . I once tried talking to my parents about investing in bitcoin, they said it was too complicated and risky as they had to keep their privatekeys , passwords , 2FA... things they have never been exposed to before . But they can go to the bank and deposit their savings without my help. I think , if bitcoin ETF is more popular in my country then I think I will introduce it to them . I believe they will consider investing in bitcoin through an ETF because it does not bring too much trouble for them .