I think Bitcoin has changed over time and circumstances, so it cannot be limited to a specific unit. Bitcoin is basically a decentralized digital currency. Where an individual enjoys the convenience of transactions without being controlled by any center. But from different people's perspectives, it is different. Some see it only as a digital currency, some see it as an investment asset, some see it as a path to financial freedom, some see it as digital gold, and some see it only as a way to get rich. I think it is wrong to limit Bitcoin to just a currency or an investment asset. Because it is a technological innovation, it is also a symbol of financial freedom and decentralization.
Theoretically, with the design of bitcoin, bitcoin is a versatile asset and can be used in many different cases as you mentioned. But in reality, we cannot deny that people tend to use it for investment purposes more than any other purpose. In my observation, up to 99% of people enter the market for profit and consider it as their main goal. Bitcoin's other use cases are secondary and people use them as an excuse to hide their real purpose of entering the market.
Not as many people use bitcoin for its original purpose as you might think.