Earlier quoted context omitted.
By the very nature of a highly skilled worker, they likely cannot realize the full value of those skills without a certain economic and commercial context. It is definitely not the case that for most H1-B employees the counterfactual is "growing their own countries out of poverty." Most likely, the counterfactual is being another 75th percentile wage worker in a low income country. In addition, this line of reasoning…
Could you please express yourself in simpler English? I cannot understand what you just said - not a native speaker.
Thus, if they go home, they will not likely be "lifting their country out of poverty"—they will just be stuck in one of the jobs that is available there. Low-skill, low-pay jobs, without any prospect for advancing to something more like they would be able to do here.
I don't know to what extent this is true, but this is my understanding of their post.