Most countries are now able to introduce the tax system especially in the GCC countries. As for the cryptocurrencies, I've read an article about the taxation of Bitcoin and Etherium in the New York Times.

Generally taxation is used by the government to increase their funds for the benefit of its constituents. Aren't cryptocurrencies decentralized? Unlike the actual bills and we use as medium for exchange/trading and investment which are all centralized and its circulation is being controlled by the government right?

If the tax system will pursue, is it fair enough seeing that the government is about to invade bitcoin? What are your insights about this?

Here is the link:
https://mobile.nytimes.com/2018/03/21/technology/think-cryptocurrency-is-confusing-try-paying-taxes-on-it.html