Sometimes grass is not greener in neighbors lawn, but sometimes it's the only place where grass exists
I will give you a factual example: Indian doctors and IT professionals who immigrated to US in 1990's as a group do much better in US now than anywhere else, including in India (I am not talking about H1 workers, I am talking about people who immigrated and achieved a Permanent Status here and professional employment). So, it was indeed a right decision for every one of those immigrants to leave India and move to a new place (in this case, US) , and they would make a mistake if they didn't do it.
Does it mean everyone from all professions from all over the world must come to US now and if they do they all will do great?
Answer is 'NO'. Because there is no factual evidence to give positive answer to this question.
Moreover, at opposite end of spectrum we have another example: we have over 10 millions of undocumented immigrants in US, over half of them from South America, and the rest from other parts of the world, who do poorly in US.
We have also many legal immigrants from other parts of the world who are neither doctors nor IT professionals, and many of them also struggle to make ends meet in US.
We also have immigrants from let's say Europe who don't find it too fascinating that US is the most religious country in the industrial world (the number of religious people in US is greater than in any other Western State) and who feel that individual Liberties within a framework of lawful society is very important part and parcel of achieving a happiness. These people also, even if able to make enough money to cover costs of living, will probably regret being in US versus being in Western Europe. (US and Western Europe have switched places on individual Liberties in the past decades).
So, the important thing to remember is: there is NO ONE place that is good for EVERYONE.
Each person naturally will look for a place where he or she can achieve their best and where they can live their life to the fullest. In US we even have this codified in Constitution, as an Inalienable Right to Pursue Happiness.
And each person should look and aspire to be where it's most suitable for thAt specific person to be.
For many Indians, who are doctors and IT professionals, who have conservative values and want material well being and social respect, US could be the best place they could ever immigrate to.
For many Western Europeans who esteem highly Individual Liberties staying where they are or moving to Canada could be the best choice.
For someone else the best destination could be their own backyard around their house, and planting the trees.
Immigration could be a very unfortunate venture for such, no matter where they go, and these people should not immigrate anywhere at all.
Each individual is different, each case is different. To make intelligent choice one must know, not only him or herself but also be fully aware of the place where they are and of the place they are planning to go. That's the only way to make the most rational choice, to move or not to move.
Best wishes to all, as always.