Bitcoin was not created to be an investment, Satoshi never mentioned that when he created Bitcoin. We are the ones who turned and used bitcoin as a profitable investment instead of using it for its original purpose but I agree that: if bitcoin was only used as a currency and did not increase in price, perhaps not many people would need it and it would not be as popular as it is now.
So far, El Salvador is the only country that considers bitcoin a legal currency.
Although what you say is true for now but it cannot be denied that for now there is a widening of meaning but it does not affect the original purpose of Satoshi actually so I think even though in the end the goal is still the same for bitcoin but it is not wrong when in this case we still use this as a form of investment because this is still very useful to do especially for now many people even for beginners know that bitcoin can be used as one aspect that can be used as an investment and it cannot be denied that for now the movement of bitcoin is known more widely because it is the impact of prices so that people compete to make this a future investment asset. race to make this an investment asset for their future.
As for making legal tender it is also very good and seeing from
this data actually apart from El Savador there is also the Central African Republic which has made bitcoin a legal tender so far.