Then instead of helping those who are already more advanced, progressive, and generally more politically stable, why not help the societies who are not advanced, progressive, and politically stable on this EARTH ?
I agree. We should help everyone on Earth. Of course, that can get a bit dicey when it enters the realm of international politics, which has led me to conclude that the best way to help humanity (as a whole) is for all the workers of the world to unify under a single banner.
On wider, I don't think reasons are secular and politically practical. are they ?
Sometimes, they're politically expedient. Social services can be a hedge against the civil disorder which can result from widespread poverty.