Bitcoin was originally created as an alternative currency, allowing anyone to use it for any purpose. However, over time, the using of Bitcoin has grown, not only as an alternative transaction tool, but also as an investment tool that can maintain the value of money in the long term, or even increase its value in the long term. Personally, I consider Bitcoin currently widely used as a very profitable investment tool if held, and this is not just for individuals, like companies, institutions, and countries also use Bitcoin as a store of value or strategic reserve. Well, besides that, I think people will actually choose Bitcoin as their entire investment one day, and I believe the main reason is "Bitcoin as legal tender" , when that happens (especially in my country), I am sure many people will transfer their fiat funds to Bitcoin, rather than holding them as fiat.
Yes you are right about Bitcoin evolution from simple currency to valuable investment and strategic reserve. You are also right that not only individuals but also companies and even some countries are now holding Bitcoin to protect against inflation. Your idea that Bitcoin becoming country legal tender would cause rush to adopt it is very compelling. However so far only two countries El Salvador and the Central African Republic have made Bitcoin legal tender and this is still very difficult and debated topic for many other nations.