It is the rule of supply and demand, when the demand goes up the price will go up also when the demand is down price will go down also.
Not only that. There are so many factors affecting the price movemnents of bitcoin. One of those are the FUDS circulations, whales manipulation, big exchanges movements and trading volumes.
Those ups and downs movements make sense because it gives us the reason and opportunity to make meaningful decisions.
In fact, we are so thankful that we have this kind of volatility in which it gives us a chance to buy at low and sell at high.
If that OP is questioning why it happens? It has been a part of crypto development and market demand. And it becomes more volatile as many traders and investors joining crypto.
That FUDs is a huge factor affecting the trend, market manipulation right nows seems not visible.