I suppose Bob could become an illegal shadow bank. The two things that define a bank are 1) regulation and supervision by the Government and 2) access to exchan

I suppose Bob could become an illegal shadow bank. The two things that define a bank are 1) regulation and supervision by the Government and 2) access to exchange settlement accounts at the central bank, but you can ignore #1 if you want (it makes it a lot more likely for customers to lose their money either by collapse or fraud) and what banks do through #2 can be done to various extents through other channels. But they’re still not quite at the same level as money creating banks as you probably can’t, say, pay taxes or receive money from the Government directly with such an entity, and probably have to launder or at least convert assets to be able to credit a normal bank account.