Well, many people, have cash that they need.  Some people do not even know what Bitcoins.  Anda lot of businesses need the credit or lending from the bank, without bank a lot of businesses would not exist. Sad but true, most of the people in almost every country is still dependent on fiat, and they know what to do with it and how to run it, but bitcoins, they may know this, but still they are more interested in fiat, so they need the bank. This has always been the way. The traditional ways of living are hard to change, people tend to stick to those familiar ways and not be willing to change it unless something beneficial comes along that makes it easy to switch. But bitcoin is not at that stage yet.