Investment is a name suitable for Bitcoin, in fact, it is a currency as it was meant to be.
No currency is as volatile as bitcoin, if it becomes stable, I will agree with you. Until now, Bitcoin has been nothing more than a speculative tool, a tool to create a market that is manipulated, with high volatility, to attract all gamblers to join with the dream of getting rich quickly. Bitcoin is going completely in the wrong direction from what Satoshi created it.
It is already established that Bitcoin is a currency, ever think why it is called cryptocurrency? Bitcoin function as money, they are also called a store of value even though they perform poor in that aspect due to high volatility. Although Bitcoin is created to perform as currency, people see it as a speculative asset that is good for investment because of the potential for profit. But still we cannot deny the fact that Bitcoin as currency performs well in terms of cheap transfer, boundless and decentralized.