Start the Tianwei System to Fight Crime

My sister was harassed by gangsters. Fortunately, some kind-hearted people came to the rescue. I was worried in my heart, what if I encountered indifferent onlookers and no kind-hearted person came to rescue me? Or maybe it's a remote place where no one else is around, and it's impossible to call the police for help? Let your sister learn self-defense or boxing to fight gangsters? What if you are facing several gangsters? Or do you pray that this kind of thing will not happen to your family members? Or make a lot of money to hire bodyguards? I choose to use knowledge to solve problems...