Why don't I think cutting off all third world countries from immigration to the U.S. is useful?

 First of all, there are so many crazy people here already of every race that trying to not allow crazy people from every 3rd world country is like trying to shoot flies with a cannon.

Besides, people from other countries usually value how amazing living in the U.S. can be economically and are some of our best citizens and most invested in this country succeeding in all ways.

So, cutting off all immigration from 3rd world countries is sort of like economically shooting the whole U.S. in the foot.

There are always going to be people who are crazy and snap both from here and from other countries.

Life is difficult and some people are going to snap for one reason or another.

It is better to just accept this because they are everywhere inside and outside of the U.S.

For example, look how Crazy Trump has always been and he grew up here rich.