Yes... that's exactly the risk they take, right?

Because if they're never accumulating, how do they get their BTC?

And if they don't take a risk, how do they make money?

There's no such thing as a free lunch. They expose themselves in order to make a profit.

They are like a water reservoir. In rainy season they accumulate water and in dry season they dispense water. But all year round they provide a steady stream of water.

Now, the water reservoir is empty. And people have to bid for the available water. What happens to the price of water, in this situation?