Bitcoin and USA dollar are two currency together, because Bitcoin is a digital currency that is only trading online or online purchasing of good's and services as the case maybe, but US dollar are seeing as a traditional money that we make use of it every day by day to buy or sell anything including online and offline transaction respectively, therefore come to talk about Bitcoin price increase and dollar price decrease during Bitcoin price pump, is a simple something all together, which is work of demand and supply in the market, when supply is high and demand will be less that affect the price of Bitcoin or dollar depreciate in price value.
Talking about the dollar specifically now, dollar depreciation is not entirely as a result of demand and supply, and this is not peculiar to the us dollar alone but to every fiat currency out there.
For bitcoin, we could say that the driving force for its ups and downs in price is as a result of demand for it, and not supply because we all know fully well that bitcoin is very limited in supply unlike fiat, that is, bitcoin supply is already fixed, so demand alone is what drive the price of bitcoin up or down, when demand is high, price goes up, and when demand is low, price goes down.
For fiat, several factors drive the price up or down in the market and in the short term, but In the long terms, fiat currencies are always losing value due to their unlimited supply nature, and for the fact that central banks even have the ability or monopoly to go on printing more fiat when governments need money, not minding the consequences of this..
So for me, bitcoin will always be a better money than fiat, though I still want both to co-exist together.