I think that you can not take cryptocurrency as "property". This is extremely not reasonable. Cryptocurrencies are digital currency, money, and imposing a tax on money is accordingly silly.
As of now, governments consider cryptocurrency as "digital assets" that being used in investment. These digital assets are like gold where prices fluctuates based on speculations. These digital coins can be classified as property. Though we know that this is not the real purpose of the coins. The question is when can we consider these coins as currency? As soon as the application of the blockchain go mainstream.