It's a market. As bitcoin goes down, amount supplied of mining/hashing goes down. Difficulty adjusts downward which shifts the supply curve a little, but nowh

It's a market. As bitcoin goes down, amount supplied of mining/hashing goes down. Difficulty adjusts downward which shifts the supply curve a little, but nowhere near enough to make it worth it to all the miners who mined before. A few percent change in difficulty doesn't make a 50% drop in bitcoin all better.