The absence of a material asset supporting the crypto currency, and anonymity in its transactions, which can lead to tax evasion, money laundering and terrorist financing, all this is of concern to Allam.
My personal opinion: Many centuries there were money laundering, and terrorism financing is not a crypto currency, it is a people's problem that they can not track, money laundering and financing of terrorism, extremism and the like, but not the problem of crypto currency.
https://www.ccn.com/bitcoin-trading-forbidden-islamic ..