So they can follow the economic development and participate in transactions and investments in Bitcoin era.
How the people of small countries can participate in participation and benefit from it?
It would be very difficult to calculate the statistics of users of each country, but the comparison of Bitcoin ATM growth from this early 2017 report can be the initial reference of the statistics.
Perhaps by the end of this year, there will be more Bitcoin ATM growth across the board due to the growing interest in bitcoin this year.
People from good countries can purchase more bitcoin than people from poor countries. Also your picture is about ATMs, not bitcoin usage. Not only do ATMs charge big fees, they need to be in countries where vandalism isn't a thing, AND their local FIAT is strong enough to be worth keeping in vaults; ie. NOT a hyperinflation. 100 dollars can buy you 0.02BTC while 500 bolivares would get you 0.00001BTC. They are both the largest banknote from their respective countries...
In country A one (1) piece of paper buys the same amount than two thousand (2000) pieces of paper in country B. Guess which country will use more ATMs...