Well there is more than 3 and a half billion people who don't have a bank account in the world and who don't live anywhere close to the bank. With a simple and cheap phone, with the Bitcoin miracles can be done.
I mean look at Mpesa in Kenya and the success of it. Bitcoin can be next Mpesa, just hundred times bigger!
Yeah, because it's easy to keep a BTCs safe in a mud hut shared by 20 in one room in Africa. Trezor?
Or for the unbanked in India living in on or next to a dump as in Dump Millionaire.... fighting for every piece of bread... keeping btcs safe will be a breeze...
NOT.....
We need ways to keep btcs safe.... easily... and safely....
Satoshi made the first major innovation... now someone needs to make it useful for the masses.
Give it time my friend, give it time. Can you remember the first computer? Now compare i5 with the current technology.
Bitcoin is still very young and time is needed to build trust and to develop and simplify this amazing tech.
All you need at the moment is a cheap android phine and you can already be your own bank. For some corners of the world this is still to much, but this will also simplify as time is passing.
Although there are some billions of people in underdeveloped areas without access to Bitcoin, there are also billions of people in underdeveloped areas with access to Bitcoin. The effects have already taken place- people living in South America, India, Indonesia, etc., all enjoy wages far more than what they would typically earn in their countries just by participating on this forums. In my opinion, THAT is the "killer app" for Bitcoin.