You are absolutely right, money kept in the bank and the one invested in Bitcoin, the return will be very different and off cause the one in Bitcoin will be more than the one in the bank and if actually one is saving them they both can bring return but not in same percentage. And one of the reason why I prefer keeping or investing in Bitcoin is that I can't easily take or withdraw unlike bank where I can easily withdraw and used it up .
I also quite understand what you are saying, but from what I see in the daily environment when someone stores money in the bank, they will actually not get anything except the amount of money they save and if the amount they save is very small, clearly there will be no interest whatsoever that they will get from the bank except for one savings specifically in their local bank. In addition, you can prove it yourself when you save more money in the bank it will actually make it difficult for you to withdraw it in a day if the amount you withdraw is very large.
This means that you can conclude that saving more money in the bank is actually not safe enough and also will not make it easy for you to withdraw it all at once in a matter of hours. It is different with customers who save money in small amounts so that they can immediately withdraw it in minutes whenever they want. While in Bitcoin anyone can save it very safely and can withdraw it whenever they want in larger amounts without being asked specific questions such as what the money is used for and where to take that much money
So what you said is actually a bit reversed from what I have seen so far because banks are not the only safest place to save money even though everyone in the world may still have a bank account for certain purposes. But it is better not to keep money in the bank for too long, especially if the amount itself is very large so that the customer can be monitored by the tax authorities because they have more assets in the form of money in your own account.