Its only a coincidence bitcoin and USD has different use and we cant compare to both of them. USD is a cash that uses for our daily needs, expenses. And bitcoin is a digital currency its like the use the first one but it uses internet and more accesible to everyone. It wont affect each other because all of the people uses them in differents a lot of ways. And if bitcoin affects the dollars then the price of it will fall also but as we can see the dollar stay on its price.