Sharia law says that a currency must have an intrinsic value. This means that money must have some use before it can be considered permissible. Any currency cannot be halal just because it is considered valuable by people. There are certain instances when financial institutions create currencies which are without intrinsic value. A currency must be backed by a commodity of actual value. Bitcoin isn’t. However, this doesn’t prevent it being counted as a currency or halal. Below are the reasons why it’s counted as a currency.

Factors that make Bitcoin have intrinsic value
Its value is dictated by demand and supply
It can be used as a currency on its own
It is mined
It is scarce