The world should have only one government rather than a national government for each country To what extent do you agree or disagree

In today’s world, it is widely perceived that one-worldism is more beneficial than one-country-one-government. Personally, I thoroughly disagree with this position.
There are numerous reasons why a global regime should not replace a multinational system, one of which is that it is difficult to adequately address the needs of every person on the global. As a result, some groups will be marginalized and the number of homeless and refugees could increase. More specifically, a universal currency, which would in turn reduction of the economic power of developed countries. At that time, the value of the currencies of major countries will simultaneously depreciate, easily causing disagreements and leading to riots.
Another justification is that the cosmocracy loses the national cultural identity of nations. When cultures imported and mixed with each other, many regions could not adapt and accept it. This would therefore decrease the diversity of cultures. It should also be noted that operating under a leader with malicious interests in mind will make the fear of totalitarianism. Instead of wars for land between countries, a single authority increased the chances of rebellion and civil war.
In sum, for the reasons mentioned above, I would argue that if the entire world were under the same government and ideological rules, then economies, and cultures, would become chaotic and terrible.