I think it's so difficult, that everyone in the world owns Bitcoin. The first reason is that its supply is limited. The second reason is that people with less capital are less interested in Bitcoin. As you yourself mentioned we also have many whales. There are large investors and large companies that are buying large amounts of Bitcoin, and some already have a lot of coins lying around. Those who have more capital are investing in it and prefer to hold it for longer. Bitcoin is not for everyone. However, if we create awareness about Bitcoin among people, the benefit will be that more and more people will be attracted to it, and will be interested in investing.
The greatest hurdle for bitcoin is the huge amount of technology and infrastructure needed to make it work, cash is just a piece of paper so it is natural that it has become widely adopted all around the world.
But even cash is not used by everyone, there are many remote communities which still use barter or that use their own currency, and bitcoin will have a lot of problems to get to those people as the requirements to use bitcoin are way higher than cash.