Once Nixon abolished the gold standard, the dollar's value quickly plummeted. The dollar index was established to give companies the ability to hedge this risk. Someone created the U.S. Dollar Index to give them a tradeable platform. Soon, banks, hedge funds, and some speculative traders entered the market. They were more interested in chasing profit than in hedging risks. 
However, proponents of sound money like Bitcoin and gold take a hesitant outlook on the long-term sustainability of floating fiat currencies. The forex market’s size and complexity are a direct result of the dissolution of Bretton Woods and are indicative of the challenges required for an international monetary order of various national floating currencies to persist without the potential for black swan events.

Moving back to predicting movements in the market, we must acknowledge that a trader must have a thorough comprehension of the factors that can affect the movement of a currency's exchange rate, if they want to be successful. Remember - there is no ultimate Forex prediction formula - it all depends on your own skills, experiences, the accuracy of your foreign exchange forecasting, and the commitment to succeeding. The five factors you need to understand are:
The foreign exchange market is the "place" where currencies are traded. Currencies are important to most people around the world, whether they realize it or not, because currencies need to be exchanged in order to conduct foreign trade and business. If you are living in the U.S. and want to buy cheese from France, either you or the company that you buy the cheese from has to pay the French for the cheese in euros (EUR). This means that the U.S. importer would have to exchange the equivalent value of U.S. dollars (USD) into euros. The same goes for traveling. A French tourist in Egypt can't pay in euros to see the pyramids because it's not the locally accepted currency. As such, the tourist has to exchange the euros for the local currency, in this case the Egyptian pound, at the current exchange rate.