Just like El Salvador, US could also try and capture the entire BTC circulating supply.
I am not sure where you got that idea from. El Salvador never attempted to purchase the entire circulating supply. How would that even work? The entire supply is not for sale. How do you purchase the coins in my cold wallet and thousands of other private wallets that people have scatter all around the world? The number of bitcoins on exchanges have never been as small as they have in recent months.
We never had "One Currency" through out the world.
And we aren't going to have that with Bitcoin either.
The company of the richest person on earth has more than a billion in Bitcoin. Some people on Wall Street have accumulated Bitcoin.
Who knows what that manipulator owns? Didn't he first say that Tesla didn't sell any of its bitcoin, but later claimed that they only sold 10% to check how much of an affect it would have on the market? More precisely, he wanted to show that it didn't have many consequences.
The thing about Peer to Peer networks is that nobody can do anything to them.
Not directly to the networks. But they can increase taxes on Bitcoin. They can make POW mining illegal. Sweden is already suggesting that to the EU. They can make it illegal to use certain exchanges, etc. There are ways for a country to hurt it, but not to stop it entirely.