According to
world bank 1.7 billion people ranging from 200 million in China and India each, 100 million range in Pakistan and Indonesia, 45 to 65 million range in Mexico, Bangladesh, Nigeria etc. This shows that a lot of rural environments have no bank. Real estate, renting a building, is one strong marketing technique used by banks to garner customers in a place. And these stats proves that banks can't reach out to all rural environment. Bitcoin on the other hand, requires only a smart phone and internet connection to send and receive bitcoin anywhere in the world; no buildings needed. It also opens a portal for users in high corrupt countries, 68.9% of 180 countries, to keep their funds safe. In Sudan for instance, Government once forced into people's houses to seize and destroy their treasures.
Hence with 1.7 billion people staying unbanked, added to the increase of people who don't rely on banks, Bitcoin provides them with numerous options why they should use bitcoin for different purposes like sending money to relatives in different countries at a very low fee.
https://www.researchgate.net/publication/370892944_Bitcoin_Is_Full_of_SurprisesThe information is true, but you should also keep in mind that in those rural areas the facility of internet is mostly absent, and without access to internet using of Bitcoin is impossible. Most of the people who belong to such areas have very little knowledge about technology, and gadgets, and for those people to adapt to Bitcoin isn't an easy thing. I know that in order to use Bitcoin you need a smartphone and internet connection, but with a smartphone and an internet connection you won't be able to purchase Bitcoin. Most people buy Bitcoin with digital form of fiat, and even that type of service is provided by banks.
No one sells Bitcoin for cash, and it's somewhat risky as well because those who are selling Bitcoin for cash could end up into prison if a country has banned Bitcoin. In current times banking system is still needed to purchase Bitcoin and we can't ignore that fact. I hope that in future the purchasing of Bitcoin won't be dependent on banks, but that thing can only happen if most people accept to trade cash or other physical items with Bitcoin.