I knew this was going to be brought up, but it's not enough to overcome the monumental salary gap. Your example of developers earning "$2k" just made me think that I invest $2k a month, not even what I save in total each month.
The living cost is obviously much different. There's still really just no comparison, in terms of net compensation.
> Assume every knowledgable person will leave their homes for 10x salary, 7x living cost and they are earning 3x of money and country will end up with idiots, slow development, slow financial growth in whole country
That's all well and good, and you're right, but the individual ends up being much better off by leaving. Brain drain, as it's called.
Rhetoric like "do it for your country" is good in theory, but individuals who leave have an opportunity to help themselves and their families out immensely via monetary gain.
It's really, really hard to ignore that.