BTC itself is central bank, BTC is money!
Banks are naturally afraid of competition, which will bring new competition to financial markets and replace some of the Banks' businesses!
Less banking means less profit!
That is true that banks may afraid of bitcoin because they knew that bitcoin cryptocurrencies has biggest value the price itself aside from that bitcoin is in progress and still continuing. In that case banks don't want to lose their earnings and find way to boom more than bitcoin. Probably banks competitive is bitcoin because the market is still expanding.