Seems more likely bitcoin was created by a big bank:

- Immediate use for it to launder money (HSBC already does this but recently got flagged by the US gov)

- Long term (if it became successful) it would enable them to reduce dependency on governments / regulation. Big banks are already more powerful than most governments and are rumored to cause political turmoil in countries to increase dependency on the bank. Why just control transactions when you can control the money itself?

- Have the financial knowledge / data to design a currency + have the technical expertise to implement it (due to the masses of quants joining banks in the past 10 years)