In what countries is it easy to find retailers and other service providers that are set up to receive Bitcoin for payment?
According to my opinion that there are eight countries for bitcoin use, namely: USA, Russia, England, Germany, Japan, China, Australia and Uni Emirat. They are the biggest countries which are suitable to use bitcoin ecosystem, even though the other countries can use too, but it's still weak and less to do it.
As far as I know, China and Russia have banned the crypto exchange markets.
This is just a information to big holder BTC to collect more BTC. China and Russia are all the biggest markets in all over the world!