Please think about two things:
(1) If LaPlata is too far, Harvard is more than 5000 miles farther.
(2) How many students from Argentina get the kind of support you need in the US? I’d guess a dozen, but probably not two. (MIT takes one student every other year). As you say, if lots of Argenine students are looking for a way out, you’ll have lots of competition. Why you?
You need a very good answer to that question, and it needs to be the centerpiece of your application. I’m afraid “because I am academically stronger than anyone you are likely to find in the USA” probably will not fly.