"以惡治惡" is one of the biggest flaws in Chinese culture.

 Do you really think that as long as the cause is just, the means to achieve it does not matter?

Do you know Chinese communist party has been using this strategy since day one? 

Just because you want to defeat "惡人", you turn yourself into something worse than "惡人". At the end, you become something worse the original problem. Is that outcome you want to see?