Then it increases to 100k but decreases to 40k, people will think it's cheap and feel more confident to buy, while they can sell the goods at a high price.

This is called a Long trap. It lures investors to FOMO in more money. It creates a bottom to buy at this price and then cleans out the rest. At this price, no one dares to short; 80% are Long and there will be an even bigger bloodbath.