Bitcoin is trying to make it popular all over the world. The dollar is accepted by many countries. You see, Bitcoin is converted to currency. Only use the dollar. And it only depends on the currency when exchanging.
The mode of purchase of bitcoin is currently based on three:
1. Fiat
2. Altcoins of which mainly is Ethereum.
Now considering the money coming in from these two sources, every market price of bitcoin will be based on the currency used to purchase the coins. Thats how the market cap and the market prices are obtained. Now we are long away from a position that bitcoin takes over fiat. Its practically not possible at this time nor is it feasible. Still we are bullish on the price and people of this forum believe in bitcoins and its properties that make it better in every sense than fiat.