Because if you spend enough time on the internet, especially the Western side, you start to hear voices of people who oppose their governments and not enough from those who support it.
Even many who are supportive tend to say that their government is authoritarian.
Nationalism does contribute to the support to the government. But The big factor for trust in any government is just material conditions that lead people to have hope that things will get better and don't have to live in constant fear. One thing I have learned from living in the West is nothing make you trust your own government more than having to live in a malicious and dysfunctional one. That's why I support the current government of Vietnam.
Damn. Where are you living currently? How is it going over there?