In recent rerun of Bones, they had a joke in which a man is asked if he knows what the penalty is for perjury. The man replied a whole lot less than murder.
It prompted a memory. Purhaps, it fit a real possibly situation. The question, why did Mrs Clinton commit the crime of destroying all the emails (also known as evidence). The reason is obvious. The penalty for destroying evidence is far less than for the crimes she was hiding.
It seems her calculation was right, especially in light of the fact that she got away with it. She never spent one day or night behind bars. Moreover, it taught the dems a lesson and they have been hiding and destroying evidence ever since.