I recommend reading this article.
As in most things in the Internet realm, it can be used for good or harm. Kali is often used for white-hat pen testing and it's a good tool for learning. Just like any tool, it can be used or abused.lochlomonder, personally, I wouldn't help a person who wants to install Kali. It is a hacking tool. So you sending him to hacking school to possibly harm society.