Holding on too tight.

How one tribe in Africa finds water: They dig a narrow hole and drop food into it. A monkey comes along and grabs the food. The monkey's hand is small enough to get in, but his fist is too big to come out with the food in his hand. It never occurs to the monkey to let go of the food. So the tribe easily captures the monkey, feeds him salt, and lets him go. The monkey heads straight to the nearest water.