[Aunche]

Aside from its transaction costs, which may be mitigated by the lightning network, Bitcoin is still a lousy currency. One important function of money is the creation of credit. If you have a large quantity of money that you don't want to spend in the short term, the money is better put to use by loaning it to a small business or couple purchasing their first house.

Without regulation or FDIC insurance, very few people would be willing to give their bitcoins to a bank so that it could be lent out to people who have a better use for it. Even if a Bitcoin bank could exist, an economic downturn could cause a liquidity crisis, where everyone tries to withdraw their Bitcoin at once. The banks would have no way of returning the Bitcoins to many of their customers. Because there is no central bank that can print out Bitcoin, the entire Bitcoin financial system would be in ruin following the crisis.