Don't you think it's kinda unfair that some extremely famous museums earn off of stolen artworks from another countries?

I think “stolen” is a complex question. Countries don’t own art, artists do. At best governments inherit art, especially ancient art, but that art really belongs to the society and in a sense is part of humanity’s patrimony, not just a single society.

So while I think societies, via their government, have some claim on art, I also think it should be wherever the most people will see and get to enjoy it.