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?
No, that's kind of the point. It's decentralized, there's no one point where you can control it. The only way to control it is to have a significant majority of the hashpower which at this point would be nearly impossible, or to break the encryption that secures the blockchain, which with the present level of technology is also nearly impossible.