Some "essential" things are not available in your country. Your country has certain things not available elsewhere. So that is how international trade was born. A bazillion years ago. Makes sense doesn't it?
But if the simpleminded nationalist populists extreme right-wing isolationists have their way there would be no foreign trade. Buy only what your country manufactures or do without. What could be simpler than that?
Okey dokey. Which country would do best doing that? Why do you think so?