Just like what has happened in Russia time and time again as their currency gets crushed by economic wars. When people see the value in their hands slipping away like sand, they run to turn it into something more solid. And a lot of people don't see bitcoin as solid right now, unfortunately.

However, it is being used more often as a protection against devaluation, like mentioned above in India, China, and other Asian countries. I'm not sure how the world would look at it if the USD loses value and reputation as a safe alternative to spiraling local currencies. They'll probably take it when the local shops run out of gold.