Eli5: Why was it world-changing that Caesar crossed the Rubicon?

Question

Eli5: Why was it world-changing that Caesar crossed the Rubicon?

In: 1397

Answer 1

It was Rome-changing because it started a great political change and ultimately a civil war that would give rise to the Imperial system over the current Republican system (which was failing)

It was Rome-changing because whatever affected Rome affected all the western world, then and in many ways up until the present.