It's easier to move (yourself and your family) to a more favorable country than to change an entire country to be more favorable, especially considering how large and complicated these nations are.
The downside is that the people leaving also tend to be the most capable of producing that change so the brain/skills-drain is self-perpetuating once it starts.
> The downside is that the people leaving also tend to be the most capable of producing that change
Some % of people, yes. But not everyone leaves. As long as enough brilliant people remain and there can be economic and scientific progress breaking the shackles of a millennia of rule, things can become right. These things are slow and take time though.
The downside is that the people leaving also tend to be the most capable of producing that change so the brain/skills-drain is self-perpetuating once it starts.