Every time I hear "but it's not faaaaair to steal the valuable educated human resources away from poor third world countries", I feel like sticking the speaker into a time machine and sending them to some really human resource-loving third world country in some really good moment, like Pol Pot's Cambodia or Francisco Macias Nguema's Equatorial Guinea.
No, don't worry. I won't really do it even if I find an appropriate time machine lying somewhere around the place.
Human resources are otherwise known as people. "Stealing them", in this context, usually refers to approving their applications for a residence permit. People are usually not owned by countries, although some countries and, apparently, an increasing number of otherwise civilized people might think otherwise.
Moving into some country is not a human right, much as some people might want to convince us otherwise. Moving out of some country, however, is. Universal Declaration of Human Rights, article 13.
This certainly does not mean that anyone is obliged to give them a new place to live. There is a number of perfectly good reasons not to let somebody in. However, not letting people in for the specific reason that their current owners might need them more would be in very bad faith as far as the Universal Declaration of Human Rights is concerned. But hey, so many people like helping the third world out of somebody else's pocket, that helping it out of somebody else's life must also feel very cool and righteous. Extra points if you manage to piss off some capitalist pigs who wanted to hire those people.
People in general tend to like sacrifice, especially when the sacrifice is being done by somebody else and they themselves are a beneficiary. "Our soldiers, who laid down their lives for our freedom,", yadda-yadda-yadda. Kinda understandable in a selfish way, really. What I don't understand is a Finnish person who demands that somebody else lay down their own life or well-being for, say, Nigeria.
If you don't want an educated Nigerian here, fine, just say it. You might not like his black face (no, I don't approve of this reason but at least it is openly and honestly irrational), you might suspect that his diploma is fake or his education is bad, you might think that there is enough unemployment in his field already, you might prefer uneducated Nigerians instead, etc. But don't say that you don't want him here because you want to help Nigeria by keeping their educated people back there. It just makes you sound pathetic. Mostly it makes you sound like a pathetic liar, because you probably don't care about Nigeria any more than I do, but if you are in fact telling the truth it makes you sound like a pathetic asshole who wants to feel good by helping third world at a great expense to somebody else. Yeah, and that Nigerian will probably move to the US or the UK anyway, but that's beside the point.
Most of the people who live in the first world have pulled a lucky ticket in the birth lottery, and the rest of us have pulled a lucky ticket in the immigration lottery. There is nothing really fair about it, but there is also no way we can really share our luck with all the rest of the world, because, let's face it, we have to look out for our own interests. It does, however, sound quite silly, when a person who lives in a nice safe rich country and gladly participates in building up its economy is talking about somebody else's obligation to build up the economy of some festering shithole.
As for third-world countries: maybe, if they want to keep their educated human resources, they should work at it? Like, pay them decent salaries? Abstain from genocide and suchlike? Keep the riots down a little bit? Or, to continue with the Equatorial Guinea's example, try not to kill people just for wearing glasses?