And right now, the bitcoin price is still below, so you can still buy at the current price. After the fall of bitcoin to its current price, it will end soon and at that time, we will see whether bitcoin will increase quickly or slowly.
Like let's say you knew that it would go from 16k levels to 30k levels in a month, and after a month it really did reach 30k, you were right and that's great, so you sell, but then after another month it went to 40k, so you failed to know how far, and you just lost a chance to make more profit.
Despite this, many people still predict where bitcoin will go, and few get it right. And it seems difficult to predict if the price will increase or decrease to a certain level.