Ref. No. 40/1177
In the name of Allah the most Gracious the most Merciful
The answer to your question is as follows:
When the bitcoin is not controlled or issued by the government, it would be regarded as a ‘fake currency’. One should avoid buying or selling such a fake currency. One day it may cause a big loss to your wealth.
And Allah knows best
Darul Uloom Waqf Deoband