This is only a guess but my guess would be that if you are using Egyptian pounds or whatever to buy Bitcoin or Monero or such that the price in that particular currency would go up although it would affect the US dollar price very little because the Egyptian pound or whatever is very small compared to the US. So when they inflate, it has very little effect due to their relative size to the rest of the nations. But when the US inflates, it makes a major change in the price because of the fact that so many people buy with US dollars.