For some reason you think that mechanically bringing people from foreign country will level the playing field. This is far from truth. You need a large and dive

For some reason you think that mechanically bringing people from foreign country will level the playing field. This is far from truth. You need a large and diverse skillset to "pilot" a developed country (make advantage of its infrastructure, give back). Once you bring in millions of uneducated, unfamiliar and uncaring people, things go south. You also lie to these people: you tell them that by leaving their communities they will land in developed paradise, but when they arrive they only see themself as 3rd sort, shunned by locals, without prospect of fruitful employment. Of course they'll radicalize. If you are serious about wanting to make world better, you should implement something like american Green Card but on grand scale. Pre-select qualified applicants by testing (build emigration schools for them perhaps, where they learn how to live in developed countries), distribute entrance permits via lottery, shape their flow, monitor their destiny so you can at any moment prove they are happier than ever, don't hurt the receiving society and productive. But this is obviously harder than "just opening the gates wide open" or "blaming for the lack of aforementioned".