It’s usually built slowly.
It usually falls quickly.
It doesn’t come from selling.
It does come from not selling.
The more it’s delivered, the stronger the positive effect is. (Exponential with almost no ceiling.)
The less it’s delivered, the stronger the negative effect is. (Exponential with an asymptote that quickly dips below zero, and far, far away from ever getting back to the point on the curve that is above zero.