> have migrated to improve their lives, not to altruistically benefit a foreign country
These are not mutually exclusive. I want a better life, and I also have career ambition and skills that I'm willing to deploy in a place that will give me a better life in return.
I'm saying most people are motivated by self interest, not that you have nothing to offer in return.
Well…your motivation is not altruistic to the host country in that case, it’s selfish.
You want a better life, the country providing it is arbitrary as long as it accepts the currency that you can provide for that better life by your skill set.
If it was altruistic you would emigrate because you believe in the country you are emigrating to even if it meant your life was worse.