This 1000℅. Honestly, even if they are paying you what you are "worth", remember the company is not your friend. (You may have friends that work there and you may feel loyal to those beside you in the trenches. That is great! But never forget that the company does not exist for your sake and you do not exist for the company!) Do what is best for you and your's and do not feel bad about it!
Someone from Asia who is pretty good at their work can get a fully international remote job that pays north of 100K USD? Is this practically possible or is it super difficult like say getting into MIT or CMU. I'm asking because this seems farfetched and I have no idea how these things actually do play out in the real world.
100k is high though; 100K in the eu is still not common at all. I know many people (with uni degrees and senior engineering positions) in Nl/uk/de who would switch jobs today if you offered something that. If wfh and reasonable interviews of course.
But they wouldn't replace him with an American for >$100k, they'd replace him with another local for $50k.
See https://remoteok.com/, etc.
If on he other hand, you are paid $200k and the colleagues are being paid $400k ... well you are well paid, might be harder to get a fully remote pay rise, but not impossible I think.
Now lets say you are paid $50k for argument sake, and you talk to your boss saying you want $100k and you can get that elsewhere. They would be crazy to let you go as $100k is still probably less than they are paying in the US if you are doing the same job.
What I have learned is the 'policy' evaporates under enough pressure. Of course they may still say no, in which case look around.
If they are paying you less than you are worth, they are not your friend, don't feel bad about moving to another job immediately.