Bitcoin was launched in 2007. It's 10 years and still no country has approved Bitcoin ?? 
and in 2018, 2nd richest man "Warren Buffet" said "bitcoin will end up badly"
There may not be any official approval for bitcoin or cryptocurrency, but I have seen unofficial approvals for bitcoin operations.and in 2018, 2nd richest man "Warren Buffet" said "bitcoin will end up badly"
I think maybe because of the bad and unethical dealings associated with bitcoin, no country has the courage to say, cryptocurrency deals are approved in their country.
One country recently announced their oil backed cryptocurrency, this is one of the unofficial approvals of cryptocurrency