There was a time where Bitcoin was not even on the radar, it was a novel idea that was primarily used by thieves and drug dealers on the dark web. Nothing to be afraid of in terms of holding a monopoly on money.
However, that same little upstart is now disrupting the system of things; from Bitcoin and other cryptocurrencies, ICOs and the ever impressive Blockchain technology. This is now a legitimate threat on traditional banks.
Banks have existed unchallenged for hundreds of years, and that is the key issue here; Bitcoin, backed by a solid platform such as Blockchain technology, is a ghost that is incredibly hard to control due to its decentralized nature.
The power and control of money is being ripped away from traditional institutions, which can also be seen on Wall Street. Some of these traditional investors are siding with what could be the future, while others vehemently denounce it.
Individuals can now enter into direct peer-to-peer trusted exchanges with strangers. They no longer need a central institution to vouch for the other party.
Just like the fax machine, the library, even metered taxis, new technologies have come along and made others obsolete. Banks are now in the sights of Bitcoin and are in their death throws, as they lash out with the power of states behind them.
However, there’s no stopping progress, and even with state-backed regulations trying to wrestle the money of the people under control, banks have every reason to be nervous.
Full news https://www.cointelegraph.com/news/why-big-banks-are-so-nervous-about-bitcoin
I'm pretty sure that a big player in the whole banks fearing Bitcoin is the fact that it currently is a form of transaction that is being used on a wide scale without being taxed. It offers a system that is significantly better than what the banks can offer people especially because of the cuts that the banks take from the people's withdrawals and deposits. With bitcoin, users have no holding back, they are free to transact as they please without giving cuts to the bank.