But at the time the assault takes place you have to do something.
...if a bystander decides to do something, yes. One could decide to defend someone other than oneself or a loved one, but there are obviously some serious risks. For one consideration, situations are not always as they appear to be at first. There are also other considerations.
* Criminals often misconstrue situations, and many of them will try to call 911 first.
* Even nearby witnesses are sometimes criminals and biased in some way against victims defending themselves. One might ask oneself when entering an area, “Is this place full of addicted zombies, creeping things,...? What are their dress and grooming like?”
* A few judicial people in Democrat or other leftist jurisdictions tend to work against self-defense, often in efforts to show questionable accomplishments. Some even hope to increase numbers of victims for the purpose of getting more funding and human resources (police state commies). If one cannot avoid being in such a jurisdiction, it’s best to wear a phone and cameras (cameras with WIFI for immediate uploads of video or photos or some other means of immediately transferring copies) along with some means of self-defense. Make calls first, then quickly upload copies of video or photos to safe sites. Install car cameras (also available with WIFI).
* Close, dark, fast. Unexpected things can happen in a flash.
* And more.
Ongoing training is very important, and no one is an expert.