for my own opinion i am agree on the idea to have the bitcoin bank. for us to know how many bitcoins do we possess and i also agree with this kind of idea for our bitcoins to be safe however it has a disadvantage which is i think the lager fees.
We don't need bank because if you want to make sure that your bitcoin is safe then buy some hardware wallet because it is a one time payment and if you buy right now then you can use that hardware wallet as your own bank and you have access to it every time and you are controlling the money that you have and there is no third party that will see your worth of money in coins.
Why do we need to use the dencentralization network for Bitcoin system? You also know use decentralization network can help us avoid the management of anyone, especially the government and banking system. Honestly, in present, there are many people do not want to put their money in the bank. But in some countries, the government is forcing people to put money in the bank and use it with limited funds.