That's true, but there are many ways to "serve the nation". Note that a foreigner who comes to work in a country will also be a tax payer, the same way a US citizen is. In addition, given the barriers to entry, they might be more qualified than the equivalent "native" employee (since the company is willing to pull the extra effort). They might become citizens after some time as well. Also, if you make it hard to hire necessary talent from abroad (as is the case in the US, and to a lesser extent in Europe as well), you end up making your own companies weaker in the process.