A true store of value does only one thing - it stores value - no reduction or increase in purchasing power ..
As of now #bitcoin is NOT a store of value because it's purchasing power is increasing - exponentially .. which is not necessarily a bad thing for an investment.. but it is precisely that - a good investment .
On the other side #gold has upheld it's purchasing power unchanged - even after 1971 - when major currencies were unpegged from gold .. albeit minor variations here and there ..