Bitcoin is known as to be the biggest cryptocurrency. in some countries it can be used to purchase goods and services and some see cryptocurrency as a threat.
if Bitcoin comes to be number one currency in the world today, can it be hijack by the government?
Hijack in other words steal? I don't think so. Unless government could access your hard earned private keys then nobody can ever access your cold wallets besides it is a crime. Furthermore, governments would probably be implementing regulations to cryptocurrencies and that would probably be worth something to them.
As of today, there are goverments that strive for access to terminal equipment connected to the internet because they want law enforcement to be able to eavesdrop end-to-end encrypted communication. If society permits this kind of access, then there wouldn't be much to keep them from also using other cryptographic keys stored on the devices, including cryptocurrency private keys.