Bitcoin cannot be stable, just as it increases in value overtime, the price might fall but the value remains. If you can hold bitcoin for a long time, it can protect your money from inflation but if you just invest with the idea of selling in the short term then i will say that it won't save your money from inflation. Only those who will hold their bitcoins for a long term will actually save it from inflation because by that time it must have added more in value unlike Fiats currency that are prone to suffer depreciation which can give birth to inflation.