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. 
Bitcoin saving is safe if you just protect it from others, yes there's a chance that you are being hacked by others but who are here letting it happened? If you trust bitcoin you can't say that bitcoin saving is not safe I think you are a negative thinker person because you always look on negative side.