Bitcoin is indeed more suitable to be used as an investment tool than central currency, in my opinion.
The reason is as you said, the high fluctuating price of Bitcoin is very unlikely to be used for central currency, but if it is used as an investment tool then it makes more sense and is more profitable.

A thousand no's to this one. Why would you want a decentralized cryptocurrency to be a world central currency? It can a major currency along with the other most frequently used and powerful currencies but as THE currency. For one, The volatility of Bitcoin alone will make a person hesitate to use it as a mode of payment, especially those that of the small consumption or small payments like the ones with a cheap or small price.

I don't think bitcoin will ever be the world's central currency.

Foremost, bitcoin is decentralized. If it will be nominated to become a global currency, it will lose its true nature. It can't be centralized and shouldn't be. Hence it's really impossible to happen. Second, the government is against everything they cannot control. Since bitcoin is decentralized, they wouldn't want it to take over because they can't regulate it much compared with fiat. Third, bitcoin is volatile. If they will make it as a global currency, they will risk so much of their resources. They don't want that. Fourth, bitcoin is scarce. It has a very limited supply. The government cannot just produce and print it like what they usually do with fiat. Lastly, bitcoin isn't recognized as currency by the government. So why would they even thought of making it a global currency? They don't acknowledge the cryptocurrencies purchasing power because it isn't legalized to most countries yet because of the aforementioned reasons.

Aside from all of this, the a lot of features must have to improve first before diving into mass adoption and into world domination (btc being global currency/reserve asset). Transaction fees are still very high while processing time takes so long to be confirmed. Hopefully these things will be enhanced for the betterment of the community and users' experience.

Yes no dout Btc more famous crypto and have a bright future but may b not because it's crypto and in crypto everything is possible  so becarefull.

The way Bitcoin is growing in popularity, it is safe to say that Bitcoin will become a central currency for the foreseeable future.Many countries are approving bitcoin anew, many countries are again on bitcoin Urging the imposition of taxes. So wait for you to become the center of Bitcoin.

Dont know about temporary currency system but would rather be an alternative decentralized payment system which is totally opposing centralization and with that alone, you could already tell that government wouldnt

really let this thing to happen that something decentralized would become mainstream or main currency and thinking off realistically on where bitcoin doesnt really fit out on some aspect which fiat could simply do.

Just let it be and it would be better on not minding about this stuff and mind off that we do have at least some options.

a country will not give up their currency but Bitcoin can be used alongside with the digital currencies that they're now developing. it's not gonna affect the income of the people whether they are paid in BTC or digital fiat, is the same thing. it will only affect if they are not going to spend it cause they may see BTC as an investment like we do today.