Because could bitcoin represents a value reserve or acts as a "digital gold", really could it change the world in a deterministic sense?
Bitcoin is more than a way to store value.
Right now it is so because there are not any real use cases for it in our real gold, thus people hodl bitcoin and wait for it to become mainstream. Its feature may change in the future as the usage of it changes through time.
In my opinion it will never change, if people are willing to hold their bitcoin when it does not have many uses why they will sell their bitcoin for fiat once a significant portion of the population of the world is using it? At that point long term holders will just use enough bitcoin to cover their necessities and to spend on luxuries but the rest of their bitcoin will be in hardware and paper wallets and they will never sell it, or at least that is what I hope they will do because that is my long term plan.