then US dollar is also an investment.
i'll tell you why. where i live the value of local currency is dropping so there are many who are now buying USD to stay ahead of the inflation that is going on. in fact they are investing in USD. and what they are doing matches the description you posted here, they will sell it in the future to get a huge profit.
but it doesn't make USD an investment. US dollar is still a currency no matter what you do with it.
the same thing is true about bitcoin. bitcoin is a currency by nature even if majority are using it as an investment.
But unfortunately because in fact many people do this, yes, hoarding dollars. I don't think we can limit a currency whether it can be an investment tool or not, as long as the price of the item fluctuates or at least not just follows the inflation rate
, then the item can be classified to have potential become an investment.