Legalizing it means allowing its citizens to mind their money freely. Some regimes just can't allow anything like this
This is the main reason many countries do not legalize bitcoin.
How many people are rich in your country? How many people are powerful in your country? How many people are in the elite in your country? How many poor and how many political parties do you have in your country?
Now observe the following: if in your country the party that is in power (the party that is governing the country) has the rich owners of everything that exists in their country, these rich people control all companies, hospitals, army, police, agencies security ... petroliferas and miners, they are in all companies, they decide the prices, they manipulate the markets, they are owners of the country, they win all the elections because of their power, you already thought if one day a fisherman buys a laptop and then invests $2000 in ETH when ETH costs only $10 and ETH rises immediately to $400, this fisherman gets a lot of money
and if there are a lot of people in a country who bought ETH and had a lot of profits, the rich people and its power will be broken, people will have money and money can overthrow a government. Coins like bitcoin are a danger to many governments