<human>: A friend and I have been arguing over Credit Unions (he thinks they are just as bad as banks, or at least will be) and he presents this argument. "Right now, Credit Unions generally don't charge fees for checking, savings, etc. They also offer very good interest rates. However, they will eventually have to start charging fees, just like the big banks do, in order to sustain themselves. How do you think Credit Unions are going to pay for the administrative fees for all those new customers that fled traditional banks? It costs money to run a bank/credit union. When a credit union increases it's customer base, costs go up. If they have enough resources, fine. However, the nature of the business dictates narrow margins to more effectively leverage the cash reserves."

I moved my money out of a big bank on November 5th and really support Credit Unions. However, I feel my knowledge is limited and I am not sure if my friend is necessarily wrong. I understand that Credit Unions are nonprofits, so a lot of considerations like profit margins aren't really an issue, plus tax exempt status, but just looking at it; If you have a bunch of free checking and savings accounts opened, and you offer them relatively high interest on their money, and ask for no fees in return, how can it not eventually start charging? This in addition to the staff they have to pay and other overhead costs. So, will Credit Unions necessarily have to start charging fees in order to sustain themselves? Or if they don't, where are they going to get the money to stay open?

Summarize the given text in a few sentences.
<bot>: As Credit Unions grow in size will they necessarily have to start charging fees in order to support the huge influx of new customers? If not, where do they make enough money to sustain the Credit Union?