Cryptocurrency is unstable but safer then bank because if you hold good coins you can multiply your money more then banks.
It's the question of safety here not about the doubling or tripling of the money. I think still a lot of people doubt about the safety of the crypto that's the reason why still they are preferring bank for the deposition of money and for the transactions. Still, more time required for them to get confidence about crypto especially about the safety of their money.