* You can have bitcoin but if it is not being tradable to fiat currency then your bitcoin has no value at all.
* You need to buy bitcoin with fiat currency without fiat currency you can't have bitcoin
* when you buy bitcoin you have to pay services like in those banks and when you like to convert bitcoin to fiat and withdraw it to a banks then you will then again to pay the service of the bank. You need also to pay the bitcoin transaction fee. So fees are everywhere from those banks to bitcoin network deducted by the miners.
* bitcoin could stand alone without being paired by fiat currency but we should make it paired with fiat to get the bitcoin with value depending on the demand of the community.
I'm not sure if you are against Bitcoin or not but you don't clearly understand what is the use of Bitcoin and the reason for its existence. Because you don't even compared FIAT money into Bitcoin in terms of value. We can both use them as a purchasing power and I actually use it often times. However, the claim that you've said about people are coverting Bitcoin into FIAT money is probably because it is not accepted in their place, and they have suppose to use it which gives them no choice.
I believe that you have knowledge in Bitcoin and in crypto, just try to capture it the whole information you've get coz for sure it helps you to fully understand it and how the system works. Digital transformation is closely coming by.