The interest you generate from banks will be stacked up on top of your initial savings deposit, while if you store/hodl Bitcoin for whatever time period, you don't actually gain anything until you start cashing them out.
In that exact same way, if the price happens to go down, you also won't lose anything until you cash out. Till that time, everything you 'lose' or 'gain' will be nothing more than a result on paper, and thus not effective.
It is true that what you gain in hodling bitcoin is paper value but it is still a upper hand than just relying on what interest the banks give you on your deposit amount. Banks do not give interest higher than inflation rate, so you actually lose value of money over time. While bitcoin gives above inflation rate interest. Though it is paper value, you can choose to cash out interest anytime you wanted.
Maybe you are right with that, bitcoin can give more profits than banks.. But when you invest into a bank you know that you are never gonna lose your money.
When you invest in bitcoin, you only invest the most you can afford to loose, and when you are gonna invest into a bank, you dont invest "$100" you have to invest a good amount of money because if you dont, then you are gonna earn pennies every month.
So in a bank you can invest 1 million dollars and you know that you are never gonna lose them... but the return is too low.
If a person has one million dollars to invest then he will surely invest in banks and won't take a risk of investing in bitcoins as even if he is getting lower returns from bank he is sure that he will surely get certain percentage of profits from it and a person who don't want to take higher risk will never invest higher capital in bitcoins.