Afghanistan War Fallacy

affirming the consequent (as it is with any narrative)

They trying to get away from someplace to someplace they believe is better. If I am in a burning building of course I am going to leave it for a place not burning. To me it sounds like some form of biases.

There might be an argument, but for now, it's an unsupported opinion.

We  could  draw out an implicit argument, but you could also ask what the person means, to see if you can parse an explicit one. 

For a good idea of what the implicit argument would look like, see Dr Bo's comment's above.

The statement seems ironic to me. The word "fleeing" is about running away from something, not running towards something. Regardless, the conclusion reached ("America is the greatest country in the world") is simply a non sequitur as it does not follow. We also can assume an implied premise which would change things a bit:

p1. People who free from a country X to country Y are proof that country Y is the greatest country in the world.

p2. People are fleeing Afghanistan to America.

C. Therefore, America is the greatest country in the world.

This is the kind of argumentative acrobatics we need to make this conclusion valid. When we do this, we can see how ridiculous premise 1 is, and just reject that premise as false.

Their argument certainly seems to be a false dilemma to me. The way you have it formulated, you certainly could not assume it's "the best", any more than me jumping out of my sinking boat into shark infested water is "the best" place I could be. If however, we have an identifiable enumeration, say A,B,C,D,E,F,G,H,I and they by vast always choose D or E, and it just so happens that D and E share centuries of similar history, culture, religion, economic system, etc, then I think it's a no brainer that those countries are considered "better" to most people than all the others.

I guess we can just dispense with that and be frank , a whole lot more people want to get into places like the US than want to get into any place in the Middle East, the areas around Persia. Basically all of the "systemically racist" countries, everybody wants to get there or we wouldn't even be having the debates that we do about mass Islamic immigration to the US, "western countries", or the Southern border etc.