Banks lend money to people who have money. It is easier to get $500,000 from a bank if you bring another $500,000 as collateral than it is to ask for just $50,000 empty handed. Therefore, banks cannot be realistically considered a stand-alone funding resource; instead, you should use bank loans as a complement to your core funding.
For example, it is possible to secure an advance from a publisher and finance the rest of your development with a bank. This can be very useful, as the lower publisher advance might allow you to negotiate better royalty rates.
The bank can also provide a credit margin to use as a buffer when the schedule slips or milestone payments don't arrive in time. A good credit margin also comes in handy when beginning the next project while awaiting royalties.