People have needs and wants they cant avoid getting back the dollar to spend.
people wants to increase their wealth so they converting bitcoin back to dollars and they buy back the bitcoin when the price is lower so they can waiting if the price is back to increase. we can see this in many exchanges that many people is willing to buy bitcoin and lower price and some of them still keep their bitcoin and only waiting one target price so they can make big profit. i am doing this too if i still have balance so i can make another profit from bitcoin pair dollars.