system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How did the suit become the worldwide pinnacle of men's fashion?
gpt
It became the central uniform of aristocracy/upper classes in the late 19th century, at the height of European (British) Imperialism. As a result it became basically the default for fashion the world over and subsequently it's been used by people in lower echelons of society to appear more wealthy/professional. Every man in the city US except for the very poor were wearing them around the turn of the 20th Century, unless they were given a special uniform by their employer.

It has been the tradition ever since, while the men's fashion world has been less focused on the style of the upper class.

edit: tl;dr The suit is essentially the grass covered front yard of fashion.