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.
LOl it depends on what government are you talking because each of them have own views and treatment to cryptocurrency.there are some whos just like what you've said as digital assets and there are some who treated this as a currency and one of the best example is Japan in which they are using bitcoin as Fiat in electronic form