I think Bitcoins saving is quite risky, because compared to other forms of investment such as gold or dollars, cryptocurrency is more risky because the possibility being hacked is so high, we could be stolen bitcoin or the ability the network system attacked, you lost all bitcoin in the second. In addition,fluctuations in bitcoin price are highly impacted by the market so investment in bitcoin is unsafe solution. 
Indeed, the value of bitcoin is unstable, and the price is determined by the market. Bitcoin is very safe if you can keep your private key and no one can steal bitcoin from your wallet.