Think about the the notion of you, being the owner of a bank. You have no money. So you borrow money to start one. Who can you borrow from? The public.

You offer savings account for people to keep their money "safe". But in actual fact you can go bankrupt too. (Plenty of examples of extinct banks)
After u get people to "save" their money in you bank you invest and make more money. And then return some small money as interest payments. - this is crowdfunding. Banks are actually borrowing money from the public.

Then here comes the nice one. If YOU, the bank boss decides revenue is so little to make yourself happy, You then offer credit cards... and if the user can't pay on time... xx% interest to be charged to the user.

So technically banks borrow money from the people and then charge a large interest by loaning back to them from the "main pool".

Think about it. If a bank wants to control cryptos...