In the 19th century China enjoyed such an abundance of labour that they felt little need for an industrial revolution. By shovelling labour into developed countries you are depriving them of the impetus to innovate. It will have terrible long term effects.
There is no law of geopolitical physics that says regime change operations must be confined to developing countries. In the event of a serious deterioration in US-EU relations you shouldn't expect the US to sit idle. The European far right does not care about Greenland one bit.
We could very well end up in a situation where we have the US and Russia working together to destabilize the EU, perhaps European leaders fear this and will let Greenland go.
55% of the 1 million Syrians living in Germany are dependent on welfare.
The act of immigrating on its own does not select for anything other than a willingness to relocate.