The journey of bitcoin from 2009 to 2017 is very interesting. Although the stories of individuals(investors) are very interesting and motivational that how they initiated and what problems they faced at earlier stages.
In 2017 the number of businesses accepting bitcoin continues to increase. Where you see the bitcoin in 2018?
You're right. Each country has a different economy and bitcoin can not become a full currency in all countries. Perhaps in the future in developed countries, it will be able to replace conventional currencies.