Banks don't force customers to petronize them, it's totally up to the discretion of the customer that they decides to bank with a particular bank or not, if you decide to take care of your money all by yourself, no one will force you not to and even while you bank with an institution, at the point you're in need of it, they will certainly give you back your money. Everything is a matter of choice and from the point of view of banks, they have to charge you if they hope to remain in business. you don't expect them to hold your money and not gain from doing so.

The only issue with banks holding your money is if they do so and when you're in need of it they are unable to remit it back to you. As long as you're getting the best treatment from them, you don't have to make it look like you're the one doing them the favour while they are not doing you any favour. If you could hold your money and not need them, you would have done it without ever seeking for the service of banks.