Bitcoin has proven to be an excellent store of value and if you disagree trying looking at a log scale. I think this is primarily because Bitcoin is a sound money that doesn’t erode from debasement like government money does.
A store of value is any commodity or asset that would normally retain purchasing power into the future and is the function of the asset that can be saved, retrieved and exchanged at a later time, and be predictably useful when retrieved.
I stand by my statement that Bitcoin is a store of value because it retains purchasing power into the future. The housing market fluctuates too and most folks consider real estate assets as a store of value.