Bitcoin is not governed or controlled by governments or banks. Hence they dont have any control over cryptocurrencies.
That said,when you sell your Bitcoin and get fiat currency like US dollar, then youre liable for taxes as per your country on capital gain.
Considering the growth of Bitcoin, you should only Buy and Hold. Take out in small amounts to avoid taxes.
Does this not make it dangerous for us though that if things crash we all crash with it? What about converting Bitcoin to gold? does tax come in then?