Why many countries choose to reject Bitcoin, because Bitcoin is decentralized and it is not liked by any country's government. Moreover, the volatile
Bitcoin price is also the reason why many countries do not accept Bitcoin as a legal tender. Fortunately there is El Salvador which is quite surprising
to many people, because it is very brave to legalize Bitcoin as a legal tender. Indeed, sometimes there needs to be a country that dares to start first,
and the government of El Salvador has the courage to make the decision to accept Bitcoin. If the government of El Salvador can demonstrate
the positive effects of its decisions, I believe many countries will follow in El Salvador's footsteps.

Well, El Salvador is already the first country that made strides in the world of Cryptocurrency by accepting it and putting it into law. Well I think El Salvador might want to try and take advantage of Bitcoin's price and they can use their resources to buy the said coin while the price is still acceptable and for them "cheap". I think they have already purchased many Bitcoins and might continue to do so and wait for the price to increase and will be able to get so much profit once they sell these.

Depends on what you mean by “it hasn’t been approved”. Some countries accept it as a means of payment and that’s a step in the right direction. And about the government, they don’t have power over the price so there’s almost no way they can approve of what they aren’t in charge of. Bitcoin is decentralized and that’s a major reason why the government haven’t ‘approved’ it.

The government won’t approve because they know they can’t control the price. The Bitcoin isn’t centralized. For the government to approve, they have to actually be in charge. It’s better that Bitcoin remains this way. So it can be decentralized.

For now the popularity of bitcoin is increasing although there are still countries that still doubt bitcoin as a legitimate currency for some reason, and for now the use of bitcoin continues to run and the price continues to increase for a long time then never hesitate to use bitcoin if later do not want to regret if there is a high increase, and every country will definitely consider giving freedom in investing in the crypto world.

Countries do hesitate to accept Bitcoin as currency as it might spoil its economy. However, it can be accepted as an asset like they do accept gold and other stuffs. Though no country has approved Bitcoin, we have huge crowd from each country who are into crypto and have invested in either Bitcoin or on any other crypto currency. So, just there is no legal approval, besides this, everything else is happening within. 

Lets put up some link for reference: https://www.nytimes.com/2021/09/07/world/americas/el-salvador-bitcoin.html
Lots had really believed out that it couldnt really be possible but El salvador did really make this thing to happen and never ever we did really expect for this thing to happen.
Those presumptions and anticipations that we do have in the past did really happen on this moment and of course there are cons and pros that we've seen
but doesnt mean that they would stop on.

Well just after a year of the question from OP. Less than a year, there's now El Salvador that has approved and now using bitcoin as a legal tender. What's more are in store for the next years to come for the other countries? We will see if at the end of this year there will be another country to adopt it as a legal tender. But with or without approval of a country as long as they don't claim bitcoin is illegal, everyone is free to use it and there is no need for any approval.

Well if I am not mistaken, there are 3 countries that already legalized bitcoin because it was followed by the El Salvador decision.
I forget the 3rd one but as far as I remember, it is El Salvador and Ukraine that already legalized bitcoin, and the third one, I did not remember.
Perhaps another year we'll pass, other countries will announce legalizing bitcoin and then other countries will follow. It is good news to us and the entire community that we are getting larger and soon bitcoin will become more expensive.

The biggest system that makes bitcoin difficult for the state to accept is decentralization, I only think the good side of a country that banned bitcoin, if it is legalized of course there will be many problems such as internet network, transaction speed and security, remember that cases of bitcoin theft we often hear, and the state does not want to be bothered with these problems.