Also explain that if we ary buying it through money and exchange it through money and save that money in our bank accounts, then how we cay say that it is not monitorised by banks? And there is no middle man in between and it is peer to peer currency? Are not we are fooling ourselves?
It's peer2peer currency when been used right, the idea behind bitcoin decentralized had nothing to do with 3rd party service providers like the banks. They're forcing their ways into the industry. When mr A buys bitcoin from mr B and the transaction is been executed without any other party knowing what the transaction was for, that's decentralization.
In transactions like this they're no middle man, don't confuse the banks you used as a payment service to be middle man instead they're only involves as a means of payment. If the transaction were excuted face to face then you'll understand why the banks in the scenario aren't middle man.
They only have the power when they serve as escrow to the transaction. With this they'll be aware what the funds passing through then are been used for.