The history as described by the research of Nick Szabo tells it differently, or some of it. The "assets" that were used as Medium of Exchange were collectibles, and because they were Stores of Value, they became the preferred Medium of Exchange. Because how could there be a social consensus develop around an "asset" to be a Medium of Exchange if the asset itself is not a Store of Value? Why would I trade my drugs with you if your Medium of Exchange is a common rock? If the rock has a Store of Value component, like a diamond, we can talk.
Bitcoin has multiple utilities and store of value is one of its utilities.
If a person owns Bitcoin, then that person can use it for many purposes: investing, trading, payment method for grocery, merchant shopping and so on. Sometimes, because of many use cases the person will not clearly clarify what he uses Bitcoin for. Utility creates value and Bitcoin has it. Deflationary creates value and Bitcoin has it too.
Even if we accept Bitcoin as a store of value or disagree with this statement, fact is fact and people naturally use Bitcoin in their own ways. Some consider and use it as a store of value. Some others don't but in general, Bitcoin adoption is increasing that is good for Bitcoin investors.