hello my fellow korean 안녕하세요 :)
nobody controls bitcoin (actually i'm not even 100% sure about this, but theoretically no single entity can control bitcoin)

having said that controlling your local exchanges is very easy. i trade myself so chances are if you're trading in korea you probably won't even have your own private key. unless you personally stash your bitcoin in an anonymous place.

if one day the government decides to crackdown on the exchanges (a very bad place to save your money) you won't be able to convert your coins into anything. you also have a heavy restriction in how much cash you can convert into krw or usd and the banks will track your every move.

i might be wrong here but who gave the government the rights to decide which coin is dangerous and which is not? people lose money all the time. let them lose it. it's part of the game.